Explicitly keep track of active HTMLMediaElements in MediaSessions.

[WebKit-https.git] / Source / WebCore / html / HTMLMediaElement.cpp

/*
 * Copyright (C) 2007-2014 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 *    notice, this list of conditions and the following disclaimer in the
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 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#include "config.h"
#if ENABLE(VIDEO)
#include "HTMLMediaElement.h"

#include "ApplicationCacheHost.h"
#include "ApplicationCacheResource.h"
#include "Attribute.h"
#include "CSSPropertyNames.h"
#include "CSSValueKeywords.h"
#include "ChromeClient.h"
#include "ClientRect.h"
#include "ClientRectList.h"
#include "ContentSecurityPolicy.h"
#include "ContentType.h"
#include "CookieJar.h"
#include "DiagnosticLoggingClient.h"
#include "DiagnosticLoggingKeys.h"
#include "DisplaySleepDisabler.h"
#include "DocumentLoader.h"
#include "ElementIterator.h"
#include "EventNames.h"
#include "ExceptionCodePlaceholder.h"
#include "FrameLoader.h"
#include "FrameLoaderClient.h"
#include "FrameView.h"
#include "HTMLSourceElement.h"
#include "HTMLVideoElement.h"
#include "JSHTMLMediaElement.h"
#include "Language.h"
#include "Logging.h"
#include "MIMETypeRegistry.h"
#include "MainFrame.h"
#include "MediaController.h"
#include "MediaControls.h"
#include "MediaDocument.h"
#include "MediaError.h"
#include "MediaFragmentURIParser.h"
#include "MediaKeyEvent.h"
#include "MediaList.h"
#include "MediaPlayer.h"
#include "MediaQueryEvaluator.h"
#include "MediaResourceLoader.h"
#include "NetworkingContext.h"
#include "PageGroup.h"
#include "PageThrottler.h"
#include "PlatformMediaSessionManager.h"
#include "ProgressTracker.h"
#include "RenderLayerCompositor.h"
#include "RenderVideo.h"
#include "RenderView.h"
#include "ResourceLoadInfo.h"
#include "ScriptController.h"
#include "ScriptSourceCode.h"
#include "SecurityPolicy.h"
#include "SessionID.h"
#include "Settings.h"
#include "ShadowRoot.h"
#include "TimeRanges.h"
#include "UserContentController.h"
#include <limits>
#include <runtime/Uint8Array.h>
#include <wtf/CurrentTime.h>
#include <wtf/MathExtras.h>
#include <wtf/Ref.h>
#include <wtf/text/CString.h>

#if ENABLE(VIDEO_TRACK)
#include "AudioTrackList.h"
#include "HTMLTrackElement.h"
#include "InbandGenericTextTrack.h"
#include "InbandTextTrackPrivate.h"
#include "InbandWebVTTTextTrack.h"
#include "RuntimeEnabledFeatures.h"
#include "TextTrackCueList.h"
#include "TextTrackList.h"
#include "VideoTrackList.h"
#endif

#if ENABLE(WEB_AUDIO)
#include "AudioSourceProvider.h"
#include "MediaElementAudioSourceNode.h"
#endif

#if PLATFORM(IOS)
#include "RuntimeApplicationChecksIOS.h"
#endif

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
#include "WebKitPlaybackTargetAvailabilityEvent.h"
#endif

#if ENABLE(MEDIA_SESSION)
#include "MediaSession.h"
#endif

#if ENABLE(MEDIA_SOURCE)
#include "DOMWindow.h"
#include "MediaSource.h"
#include "Performance.h"
#include "VideoPlaybackQuality.h"
#endif

#if ENABLE(MEDIA_STREAM)
#include "MediaStream.h"
#include "MediaStreamRegistry.h"
#endif

#if ENABLE(ENCRYPTED_MEDIA_V2)
#include "MediaKeyNeededEvent.h"
#include "MediaKeys.h"
#endif

#if USE(PLATFORM_TEXT_TRACK_MENU)
#include "PlatformTextTrack.h"
#endif

#if ENABLE(MEDIA_CONTROLS_SCRIPT)
#include "JSMediaControlsHost.h"
#include "MediaControlsHost.h"
#include "ScriptGlobalObject.h"
#include <bindings/ScriptObject.h>
#endif

namespace WebCore {

static const double SeekRepeatDelay = 0.1;
static const double SeekTime = 0.2;
static const double ScanRepeatDelay = 1.5;
static const double ScanMaximumRate = 8;

static void setFlags(unsigned& value, unsigned flags)
{
    value |= flags;
}

static void clearFlags(unsigned& value, unsigned flags)
{
    value &= ~flags;
}
    
#if !LOG_DISABLED
static String urlForLoggingMedia(const URL& url)
{
    static const unsigned maximumURLLengthForLogging = 128;

    if (url.string().length() < maximumURLLengthForLogging)
        return url.string();
    return url.string().substring(0, maximumURLLengthForLogging) + "...";
}

static const char* boolString(bool val)
{
    return val ? "true" : "false";
}
#endif

#ifndef LOG_MEDIA_EVENTS
// Default to not logging events because so many are generated they can overwhelm the rest of 
// the logging.
#define LOG_MEDIA_EVENTS 0
#endif

#ifndef LOG_CACHED_TIME_WARNINGS
// Default to not logging warnings about excessive drift in the cached media time because it adds a
// fair amount of overhead and logging.
#define LOG_CACHED_TIME_WARNINGS 0
#endif

#if ENABLE(MEDIA_SOURCE)
// URL protocol used to signal that the media source API is being used.
static const char* mediaSourceBlobProtocol = "blob";
#endif

using namespace HTMLNames;

typedef HashMap<Document*, HashSet<HTMLMediaElement*>> DocumentElementSetMap;
static DocumentElementSetMap& documentToElementSetMap()
{
    DEPRECATED_DEFINE_STATIC_LOCAL(DocumentElementSetMap, map, ());
    return map;
}

static void addElementToDocumentMap(HTMLMediaElement& element, Document& document)
{
    DocumentElementSetMap& map = documentToElementSetMap();
    HashSet<HTMLMediaElement*> set = map.take(&document);
    set.add(&element);
    map.add(&document, set);
}

static void removeElementFromDocumentMap(HTMLMediaElement& element, Document& document)
{
    DocumentElementSetMap& map = documentToElementSetMap();
    HashSet<HTMLMediaElement*> set = map.take(&document);
    set.remove(&element);
    if (!set.isEmpty())
        map.add(&document, set);
}

#if ENABLE(ENCRYPTED_MEDIA)
static ExceptionCode exceptionCodeForMediaKeyException(MediaPlayer::MediaKeyException exception)
{
    switch (exception) {
    case MediaPlayer::NoError:
        return 0;
    case MediaPlayer::InvalidPlayerState:
        return INVALID_STATE_ERR;
    case MediaPlayer::KeySystemNotSupported:
        return NOT_SUPPORTED_ERR;
    }

    ASSERT_NOT_REACHED();
    return INVALID_STATE_ERR;
}
#endif

#if ENABLE(VIDEO_TRACK)
class TrackDisplayUpdateScope {
public:
    TrackDisplayUpdateScope(HTMLMediaElement* mediaElement)
    {
        m_mediaElement = mediaElement;
        m_mediaElement->beginIgnoringTrackDisplayUpdateRequests();
    }
    ~TrackDisplayUpdateScope()
    {
        ASSERT(m_mediaElement);
        m_mediaElement->endIgnoringTrackDisplayUpdateRequests();
    }
    
private:
    HTMLMediaElement* m_mediaElement;
};
#endif

struct HTMLMediaElement::TrackGroup {
    enum GroupKind { CaptionsAndSubtitles, Description, Chapter, Metadata, Other };

    TrackGroup(GroupKind kind)
        : visibleTrack(0)
        , defaultTrack(0)
        , kind(kind)
        , hasSrcLang(false)
    {
    }

    Vector<RefPtr<TextTrack>> tracks;
    RefPtr<TextTrack> visibleTrack;
    RefPtr<TextTrack> defaultTrack;
    GroupKind kind;
    bool hasSrcLang;
};

HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName, Document& document, bool createdByParser)
    : HTMLElement(tagName, document)
    , ActiveDOMObject(&document)
    , m_pendingActionTimer(*this, &HTMLMediaElement::pendingActionTimerFired)
    , m_progressEventTimer(*this, &HTMLMediaElement::progressEventTimerFired)
    , m_playbackProgressTimer(*this, &HTMLMediaElement::playbackProgressTimerFired)
    , m_scanTimer(*this, &HTMLMediaElement::scanTimerFired)
    , m_seekTaskQueue(document)
    , m_resizeTaskQueue(document)
    , m_shadowDOMTaskQueue(document)
    , m_playedTimeRanges()
    , m_asyncEventQueue(*this)
    , m_requestedPlaybackRate(1)
    , m_reportedPlaybackRate(1)
    , m_defaultPlaybackRate(1)
    , m_webkitPreservesPitch(true)
    , m_networkState(NETWORK_EMPTY)
    , m_readyState(HAVE_NOTHING)
    , m_readyStateMaximum(HAVE_NOTHING)
    , m_volume(1.0f)
    , m_volumeInitialized(false)
    , m_previousProgressTime(std::numeric_limits<double>::max())
    , m_clockTimeAtLastUpdateEvent(0)
    , m_lastTimeUpdateEventMovieTime(MediaTime::positiveInfiniteTime())
    , m_loadState(WaitingForSource)
    , m_videoFullscreenMode(VideoFullscreenModeNone)
#if PLATFORM(IOS)
    , m_videoFullscreenGravity(MediaPlayer::VideoGravityResizeAspect)
#endif
    , m_preload(MediaPlayer::Auto)
    , m_displayMode(Unknown)
    , m_processingMediaPlayerCallback(0)
#if ENABLE(MEDIA_SOURCE)
    , m_droppedVideoFrames(0)
#endif
    , m_clockTimeAtLastCachedTimeUpdate(0)
    , m_minimumClockTimeToUpdateCachedTime(0)
    , m_pendingActionFlags(0)
    , m_actionAfterScan(Nothing)
    , m_scanType(Scan)
    , m_scanDirection(Forward)
    , m_firstTimePlaying(true)
    , m_playing(false)
    , m_isWaitingUntilMediaCanStart(false)
    , m_shouldDelayLoadEvent(false)
    , m_haveFiredLoadedData(false)
    , m_inActiveDocument(true)
    , m_autoplaying(true)
    , m_muted(false)
    , m_explicitlyMuted(false)
    , m_paused(true)
    , m_seeking(false)
    , m_sentStalledEvent(false)
    , m_sentEndEvent(false)
    , m_pausedInternal(false)
    , m_sendProgressEvents(true)
    , m_closedCaptionsVisible(false)
    , m_webkitLegacyClosedCaptionOverride(false)
    , m_completelyLoaded(false)
    , m_havePreparedToPlay(false)
    , m_parsingInProgress(createdByParser)
    , m_elementIsHidden(document.hidden())
#if ENABLE(MEDIA_CONTROLS_SCRIPT)
    , m_mediaControlsDependOnPageScaleFactor(false)
#endif
#if ENABLE(VIDEO_TRACK)
    , m_tracksAreReady(true)
    , m_haveVisibleTextTrack(false)
    , m_processingPreferenceChange(false)
    , m_lastTextTrackUpdateTime(MediaTime(-1, 1))
    , m_captionDisplayMode(CaptionUserPreferences::Automatic)
    , m_audioTracks(0)
    , m_textTracks(0)
    , m_videoTracks(0)
    , m_ignoreTrackDisplayUpdate(0)
#endif
#if ENABLE(WEB_AUDIO)
    , m_audioSourceNode(0)
#endif
    , m_mediaSession(std::make_unique<MediaElementSession>(*this))
    , m_reportedExtraMemoryCost(0)
#if ENABLE(MEDIA_STREAM)
    , m_mediaStreamSrcObject(nullptr)
#endif
{
    LOG(Media, "HTMLMediaElement::HTMLMediaElement(%p)", this);
    setHasCustomStyleResolveCallbacks();

    m_mediaSession->addBehaviorRestriction(MediaElementSession::RequireUserGestureForFullscreen);
    m_mediaSession->addBehaviorRestriction(MediaElementSession::RequirePageConsentToLoadMedia);
#if ENABLE(WIRELESS_PLAYBACK_TARGET)
    m_mediaSession->addBehaviorRestriction(MediaElementSession::RequireUserGestureToAutoplayToExternalDevice);
#endif

    // FIXME: We should clean up and look to better merge the iOS and non-iOS code below.
    Settings* settings = document.settings();
#if !PLATFORM(IOS)
    if (settings && settings->requiresUserGestureForMediaPlayback()) {
        m_mediaSession->addBehaviorRestriction(MediaElementSession::RequireUserGestureForRateChange);
        m_mediaSession->addBehaviorRestriction(MediaElementSession::RequireUserGestureForLoad);
    }
#else
    m_sendProgressEvents = false;
    if (!settings || settings->requiresUserGestureForMediaPlayback()) {
        // Allow autoplay in a MediaDocument that is not in an iframe.
        if (document.ownerElement() || !document.isMediaDocument())
            m_mediaSession->addBehaviorRestriction(MediaElementSession::RequireUserGestureForRateChange);
#if ENABLE(WIRELESS_PLAYBACK_TARGET)
        m_mediaSession->addBehaviorRestriction(MediaElementSession::RequireUserGestureToShowPlaybackTargetPicker);
#endif
    } else {
        // Relax RequireUserGestureForFullscreen when requiresUserGestureForMediaPlayback is not set:
        m_mediaSession->removeBehaviorRestriction(MediaElementSession::RequireUserGestureForFullscreen);
    }
#endif // !PLATFORM(IOS)

    if (settings && settings->audioPlaybackRequiresUserGesture())
        m_mediaSession->addBehaviorRestriction(MediaElementSession::RequireUserGestureForAudioRateChange);

#if ENABLE(VIDEO_TRACK)
    if (document.page())
        m_captionDisplayMode = document.page()->group().captionPreferences()->captionDisplayMode();
#endif

    registerWithDocument(document);
}

HTMLMediaElement::~HTMLMediaElement()
{
    LOG(Media, "HTMLMediaElement::~HTMLMediaElement(%p)", this);

    m_asyncEventQueue.close();

    setShouldDelayLoadEvent(false);
    unregisterWithDocument(document());

#if ENABLE(VIDEO_TRACK)
    if (m_audioTracks) {
        m_audioTracks->clearElement();
        for (unsigned i = 0; i < m_audioTracks->length(); ++i)
            m_audioTracks->item(i)->clearClient();
    }
    if (m_textTracks)
        m_textTracks->clearElement();
    if (m_textTracks) {
        for (unsigned i = 0; i < m_textTracks->length(); ++i)
            m_textTracks->item(i)->clearClient();
    }
    if (m_videoTracks) {
        m_videoTracks->clearElement();
        for (unsigned i = 0; i < m_videoTracks->length(); ++i)
            m_videoTracks->item(i)->clearClient();
    }
#endif

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
    if (hasEventListeners(eventNames().webkitplaybacktargetavailabilitychangedEvent)) {
        m_hasPlaybackTargetAvailabilityListeners = false;
        m_mediaSession->setHasPlaybackTargetAvailabilityListeners(*this, false);
        updateMediaState();
    }
#endif

    if (m_mediaController) {
        m_mediaController->removeMediaElement(this);
        m_mediaController = 0;
    }

#if ENABLE(MEDIA_SOURCE)
    closeMediaSource();
#endif

#if ENABLE(ENCRYPTED_MEDIA_V2)
    setMediaKeys(0);
#endif

#if ENABLE(MEDIA_CONTROLS_SCRIPT)
    if (m_isolatedWorld)
        m_isolatedWorld->clearWrappers();
#endif

#if ENABLE(MEDIA_SESSION)
    if (m_session) {
        m_session->removeMediaElement(*this);
        m_session = nullptr;
    }
#endif

    m_seekTaskQueue.close();

    m_completelyLoaded = true;
}

void HTMLMediaElement::registerWithDocument(Document& document)
{
    m_mediaSession->registerWithDocument(document);

    if (m_isWaitingUntilMediaCanStart)
        document.addMediaCanStartListener(this);

#if !PLATFORM(IOS)
    document.registerForMediaVolumeCallbacks(this);
    document.registerForPrivateBrowsingStateChangedCallbacks(this);
#endif

    document.registerForVisibilityStateChangedCallbacks(this);

#if ENABLE(VIDEO_TRACK)
    if (m_requireCaptionPreferencesChangedCallbacks)
        document.registerForCaptionPreferencesChangedCallbacks(this);
#endif

#if ENABLE(MEDIA_CONTROLS_SCRIPT)
    if (m_mediaControlsDependOnPageScaleFactor)
        document.registerForPageScaleFactorChangedCallbacks(this);
#endif

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
    document.registerForPageCacheSuspensionCallbacks(this);
#endif

    document.addAudioProducer(this);
    addElementToDocumentMap(*this, document);
}

void HTMLMediaElement::unregisterWithDocument(Document& document)
{
    m_mediaSession->unregisterWithDocument(document);

    if (m_isWaitingUntilMediaCanStart)
        document.removeMediaCanStartListener(this);

#if !PLATFORM(IOS)
    document.unregisterForMediaVolumeCallbacks(this);
    document.unregisterForPrivateBrowsingStateChangedCallbacks(this);
#endif

    document.unregisterForVisibilityStateChangedCallbacks(this);

#if ENABLE(VIDEO_TRACK)
    if (m_requireCaptionPreferencesChangedCallbacks)
        document.unregisterForCaptionPreferencesChangedCallbacks(this);
#endif

#if ENABLE(MEDIA_CONTROLS_SCRIPT)
    if (m_mediaControlsDependOnPageScaleFactor)
        document.unregisterForPageScaleFactorChangedCallbacks(this);
#endif

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
    document.unregisterForPageCacheSuspensionCallbacks(this);
#endif

    document.removeAudioProducer(this);
    removeElementFromDocumentMap(*this, document);
}

void HTMLMediaElement::didMoveToNewDocument(Document* oldDocument)
{
    if (m_shouldDelayLoadEvent) {
        if (oldDocument)
            oldDocument->decrementLoadEventDelayCount();
        document().incrementLoadEventDelayCount();
    }

    if (oldDocument)
        unregisterWithDocument(*oldDocument);

    registerWithDocument(document());

    HTMLElement::didMoveToNewDocument(oldDocument);
}

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
void HTMLMediaElement::documentWillSuspendForPageCache()
{
    m_mediaSession->unregisterWithDocument(document());
}

void HTMLMediaElement::documentDidResumeFromPageCache()
{
    m_mediaSession->registerWithDocument(document());
}
#endif

bool HTMLMediaElement::hasCustomFocusLogic() const
{
    return true;
}

bool HTMLMediaElement::supportsFocus() const
{
    if (document().isMediaDocument())
        return false;

    // If no controls specified, we should still be able to focus the element if it has tabIndex.
    return controls() ||  HTMLElement::supportsFocus();
}

bool HTMLMediaElement::isMouseFocusable() const
{
    return false;
}

void HTMLMediaElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
{
    if (name == srcAttr) {
#if PLATFORM(IOS)
        // Note, unless the restriction on requiring user action has been removed,
        // do not begin downloading data on iOS.
        if (!value.isNull() && m_mediaSession->dataLoadingPermitted(*this))
#else
        // Trigger a reload, as long as the 'src' attribute is present.
        if (!value.isNull())
#endif
        {
            clearMediaPlayer(LoadMediaResource);
            scheduleDelayedAction(LoadMediaResource);
        }
    } else if (name == controlsAttr)
        configureMediaControls();
    else if (name == loopAttr)
        updateSleepDisabling();
    else if (name == preloadAttr) {
        if (equalIgnoringCase(value, "none"))
            m_preload = MediaPlayer::None;
        else if (equalIgnoringCase(value, "metadata"))
            m_preload = MediaPlayer::MetaData;
        else {
            // The spec does not define an "invalid value default" but "auto" is suggested as the
            // "missing value default", so use it for everything except "none" and "metadata"
            m_preload = MediaPlayer::Auto;
        }

        // The attribute must be ignored if the autoplay attribute is present
        if (!autoplay() && m_player)
            m_player->setPreload(m_mediaSession->effectivePreloadForElement(*this));

    } else if (name == mediagroupAttr)
        setMediaGroup(value);
    else
        HTMLElement::parseAttribute(name, value);
}

void HTMLMediaElement::finishParsingChildren()
{
    HTMLElement::finishParsingChildren();
    m_parsingInProgress = false;
    
#if ENABLE(VIDEO_TRACK)
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    if (descendantsOfType<HTMLTrackElement>(*this).first())
        scheduleDelayedAction(ConfigureTextTracks);
#endif
}

bool HTMLMediaElement::rendererIsNeeded(const RenderStyle& style)
{
    return controls() && HTMLElement::rendererIsNeeded(style);
}

RenderPtr<RenderElement> HTMLMediaElement::createElementRenderer(Ref<RenderStyle>&& style, const RenderTreePosition&)
{
    return createRenderer<RenderMedia>(*this, WTF::move(style));
}

bool HTMLMediaElement::childShouldCreateRenderer(const Node& child) const
{
#if ENABLE(MEDIA_CONTROLS_SCRIPT)
    return hasShadowRootParent(child) && HTMLElement::childShouldCreateRenderer(child);
#else
    if (!hasMediaControls())
        return false;
    // <media> doesn't allow its content, including shadow subtree, to
    // be rendered. So this should return false for most of the children.
    // One exception is a shadow tree built for rendering controls which should be visible.
    // So we let them go here by comparing its subtree root with one of the controls.
    return &mediaControls()->treeScope() == &child.treeScope()
        && hasShadowRootParent(child)
        && HTMLElement::childShouldCreateRenderer(child);
#endif
}

Node::InsertionNotificationRequest HTMLMediaElement::insertedInto(ContainerNode& insertionPoint)
{
    LOG(Media, "HTMLMediaElement::insertedInto(%p)", this);

    HTMLElement::insertedInto(insertionPoint);
    if (insertionPoint.inDocument()) {
        m_inActiveDocument = true;

#if PLATFORM(IOS)
        if (m_networkState == NETWORK_EMPTY && !fastGetAttribute(srcAttr).isEmpty() && m_mediaSession->dataLoadingPermitted(*this))
#else
        if (m_networkState == NETWORK_EMPTY && !fastGetAttribute(srcAttr).isEmpty())
#endif
            scheduleDelayedAction(LoadMediaResource);
    }

    if (!m_explicitlyMuted) {
        m_explicitlyMuted = true;
        m_muted = fastHasAttribute(mutedAttr);
    }

    configureMediaControls();
    return InsertionDone;
}

void HTMLMediaElement::removedFrom(ContainerNode& insertionPoint)
{
    LOG(Media, "HTMLMediaElement::removedFrom(%p)", this);

    m_inActiveDocument = false;
    if (insertionPoint.inDocument()) {
        if (hasMediaControls())
            mediaControls()->hide();
        if (m_networkState > NETWORK_EMPTY)
            pause();
        if (m_videoFullscreenMode != VideoFullscreenModeNone)
            exitFullscreen();

        if (m_player) {
            size_t extraMemoryCost = m_player->extraMemoryCost();
            if (extraMemoryCost > m_reportedExtraMemoryCost) {
                JSC::VM& vm = JSDOMWindowBase::commonVM();
                JSC::JSLockHolder lock(vm);

                size_t extraMemoryCostDelta = extraMemoryCost - m_reportedExtraMemoryCost;
                m_reportedExtraMemoryCost = extraMemoryCost;
                // FIXME: Adopt reportExtraMemoryVisited, and switch to reportExtraMemoryAllocated.
                // https://bugs.webkit.org/show_bug.cgi?id=142595
                vm.heap.deprecatedReportExtraMemory(extraMemoryCostDelta);
            }
        }
    }

    HTMLElement::removedFrom(insertionPoint);
}

void HTMLMediaElement::willAttachRenderers()
{
    ASSERT(!renderer());
}

void HTMLMediaElement::didAttachRenderers()
{
    if (renderer())
        renderer()->updateFromElement();
}

void HTMLMediaElement::didRecalcStyle(Style::Change)
{
    if (renderer())
        renderer()->updateFromElement();
}

void HTMLMediaElement::scheduleDelayedAction(DelayedActionType actionType)
{
    LOG(Media, "HTMLMediaElement::scheduleLoad(%p)", this);

    if ((actionType & LoadMediaResource) && !(m_pendingActionFlags & LoadMediaResource)) {
        prepareForLoad();
        setFlags(m_pendingActionFlags, LoadMediaResource);
    }

#if ENABLE(VIDEO_TRACK)
    if (RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled() && (actionType & ConfigureTextTracks))
        setFlags(m_pendingActionFlags, ConfigureTextTracks);
#endif

#if USE(PLATFORM_TEXT_TRACK_MENU)
    if (actionType & TextTrackChangesNotification)
        setFlags(m_pendingActionFlags, TextTrackChangesNotification);
#endif

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
    if (actionType & CheckPlaybackTargetCompatablity)
        setFlags(m_pendingActionFlags, CheckPlaybackTargetCompatablity);
#endif

    m_pendingActionTimer.startOneShot(0);
}

void HTMLMediaElement::scheduleNextSourceChild()
{
    // Schedule the timer to try the next <source> element WITHOUT resetting state ala prepareForLoad.
    setFlags(m_pendingActionFlags, LoadMediaResource);
    m_pendingActionTimer.startOneShot(0);
}

void HTMLMediaElement::scheduleEvent(const AtomicString& eventName)
{
#if LOG_MEDIA_EVENTS
    LOG(Media, "HTMLMediaElement::scheduleEvent(%p) - scheduling '%s'", this, eventName.string().ascii().data());
#endif
    RefPtr<Event> event = Event::create(eventName, false, true);
    
    // Don't set the event target, the event queue will set it in GenericEventQueue::timerFired and setting it here
    // will trigger an ASSERT if this element has been marked for deletion.

    m_asyncEventQueue.enqueueEvent(event.release());
}

void HTMLMediaElement::pendingActionTimerFired()
{
    Ref<HTMLMediaElement> protect(*this); // loadNextSourceChild may fire 'beforeload', which can make arbitrary DOM mutations.

#if ENABLE(VIDEO_TRACK)
    if (RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled() && (m_pendingActionFlags & ConfigureTextTracks))
        configureTextTracks();
#endif

    if (m_pendingActionFlags & LoadMediaResource) {
        if (m_loadState == LoadingFromSourceElement)
            loadNextSourceChild();
        else
            loadInternal();
    }

#if USE(PLATFORM_TEXT_TRACK_MENU)
    if (RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled() && (m_pendingActionFlags & TextTrackChangesNotification))
        notifyMediaPlayerOfTextTrackChanges();
#endif

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
    if (m_pendingActionFlags & CheckPlaybackTargetCompatablity && m_player && m_player->isCurrentPlaybackTargetWireless() && !m_player->canPlayToWirelessPlaybackTarget()) {
        LOG(Media, "HTMLMediaElement::pendingActionTimerFired(%p) - calling setShouldPlayToPlaybackTarget(false)", this);
        m_player->setShouldPlayToPlaybackTarget(false);
    }
#endif

    m_pendingActionFlags = 0;
}

PassRefPtr<MediaError> HTMLMediaElement::error() const 
{
    return m_error;
}

void HTMLMediaElement::setSrc(const String& url)
{
    setAttribute(srcAttr, url);
}

#if ENABLE(MEDIA_STREAM)
void HTMLMediaElement::setSrcObject(MediaStream* mediaStream)
{
    // FIXME: Setting the srcObject attribute may cause other changes to the media element's internal state:
    // Specifically, if srcObject is specified, the UA must use it as the source of media, even if the src
    // attribute is also set or children are present. If the value of srcObject is replaced or set to null
    // the UA must re-run the media element load algorithm.
    //
    // https://bugs.webkit.org/show_bug.cgi?id=124896

    m_mediaStreamSrcObject = mediaStream;
}
#endif

HTMLMediaElement::NetworkState HTMLMediaElement::networkState() const
{
    return m_networkState;
}

String HTMLMediaElement::canPlayType(const String& mimeType, const String& keySystem, const URL& url) const
{
    MediaEngineSupportParameters parameters;
    ContentType contentType(mimeType);
    parameters.type = contentType.type().lower();
    parameters.codecs = contentType.parameter(ASCIILiteral("codecs"));
    parameters.url = url;
#if ENABLE(ENCRYPTED_MEDIA)
    parameters.keySystem = keySystem;
#else
    UNUSED_PARAM(keySystem);
#endif
    MediaPlayer::SupportsType support = MediaPlayer::supportsType(parameters, this);
    String canPlay;

    // 4.8.10.3
    switch (support)
    {
        case MediaPlayer::IsNotSupported:
            canPlay = emptyString();
            break;
        case MediaPlayer::MayBeSupported:
            canPlay = ASCIILiteral("maybe");
            break;
        case MediaPlayer::IsSupported:
            canPlay = ASCIILiteral("probably");
            break;
    }
    
    LOG(Media, "HTMLMediaElement::canPlayType(%p) - [%s, %s, %s] -> %s", this, mimeType.utf8().data(), keySystem.utf8().data(), url.stringCenterEllipsizedToLength().utf8().data(), canPlay.utf8().data());

    return canPlay;
}

void HTMLMediaElement::load()
{
    Ref<HTMLMediaElement> protect(*this); // loadInternal may result in a 'beforeload' event, which can make arbitrary DOM mutations.
    
    LOG(Media, "HTMLMediaElement::load(%p)", this);
    
    if (!m_mediaSession->dataLoadingPermitted(*this))
        return;
    if (ScriptController::processingUserGesture())
        removeBehaviorsRestrictionsAfterFirstUserGesture();

    prepareForLoad();
    loadInternal();
    prepareToPlay();
}

void HTMLMediaElement::prepareForLoad()
{
    LOG(Media, "HTMLMediaElement::prepareForLoad(%p)", this);

    // Perform the cleanup required for the resource load algorithm to run.
    stopPeriodicTimers();
    m_pendingActionTimer.stop();
    // FIXME: Figure out appropriate place to reset LoadTextTrackResource if necessary and set m_pendingActionFlags to 0 here.
    m_pendingActionFlags &= ~LoadMediaResource;
    m_sentEndEvent = false;
    m_sentStalledEvent = false;
    m_haveFiredLoadedData = false;
    m_completelyLoaded = false;
    m_havePreparedToPlay = false;
    m_displayMode = Unknown;
    m_currentSrc = URL();

    // 1 - Abort any already-running instance of the resource selection algorithm for this element.
    m_loadState = WaitingForSource;
    m_currentSourceNode = 0;

    // 2 - If there are any tasks from the media element's media element event task source in 
    // one of the task queues, then remove those tasks.
    cancelPendingEventsAndCallbacks();

    // 3 - If the media element's networkState is set to NETWORK_LOADING or NETWORK_IDLE, queue
    // a task to fire a simple event named abort at the media element.
    if (m_networkState == NETWORK_LOADING || m_networkState == NETWORK_IDLE)
        scheduleEvent(eventNames().abortEvent);

#if ENABLE(MEDIA_SOURCE)
    closeMediaSource();
#endif

    createMediaPlayer();

    // 4 - If the media element's networkState is not set to NETWORK_EMPTY, then run these substeps
    if (m_networkState != NETWORK_EMPTY) {
        // 4.1 - Queue a task to fire a simple event named emptied at the media element.
        scheduleEvent(eventNames().emptiedEvent);

        // 4.2 - If a fetching process is in progress for the media element, the user agent should stop it.
        m_networkState = NETWORK_EMPTY;

        // 4.3 - Forget the media element's media-resource-specific tracks.
        forgetResourceSpecificTracks();

        // 4.4 - If readyState is not set to HAVE_NOTHING, then set it to that state.
        m_readyState = HAVE_NOTHING;
        m_readyStateMaximum = HAVE_NOTHING;

        // 4.5 - If the paused attribute is false, then set it to true.
        m_paused = true;

        // 4.6 - If seeking is true, set it to false.
        m_seeking = false;

        // 4.7 - Set the current playback position to 0.
        //       Set the official playback position to 0.
        //       If this changed the official playback position, then queue a task to fire a simple event named timeupdate at the media element.
        // FIXME: Add support for firing this event. e.g., scheduleEvent(eventNames().timeUpdateEvent);

        // 4.8 - Set the initial playback position to 0.
        // FIXME: Make this less subtle. The position only becomes 0 because of the createMediaPlayer() call
        // above.
        refreshCachedTime();

        invalidateCachedTime();

        // 4.9 - Set the timeline offset to Not-a-Number (NaN).
        // 4.10 - Update the duration attribute to Not-a-Number (NaN).

        updateMediaController();
#if ENABLE(VIDEO_TRACK)
        if (RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
            updateActiveTextTrackCues(MediaTime::zeroTime());
#endif
    }

    // 5 - Set the playbackRate attribute to the value of the defaultPlaybackRate attribute.
    setPlaybackRate(defaultPlaybackRate());

    // 6 - Set the error attribute to null and the autoplaying flag to true.
    m_error = 0;
    m_autoplaying = true;

    // 7 - Invoke the media element's resource selection algorithm.

    // 8 - Note: Playback of any previously playing media resource for this element stops.

    // The resource selection algorithm
    // 1 - Set the networkState to NETWORK_NO_SOURCE
    m_networkState = NETWORK_NO_SOURCE;

    // 2 - Asynchronously await a stable state.

    m_playedTimeRanges = TimeRanges::create();

    // FIXME: Investigate whether these can be moved into m_networkState != NETWORK_EMPTY block above
    // so they are closer to the relevant spec steps.
    m_lastSeekTime = MediaTime::zeroTime();

    // The spec doesn't say to block the load event until we actually run the asynchronous section
    // algorithm, but do it now because we won't start that until after the timer fires and the 
    // event may have already fired by then.
    MediaPlayer::Preload effectivePreload = m_mediaSession->effectivePreloadForElement(*this);
    if (effectivePreload != MediaPlayer::None)
        setShouldDelayLoadEvent(true);

#if PLATFORM(IOS)
    Settings* settings = document().settings();
    if (effectivePreload != MediaPlayer::None && settings && settings->mediaDataLoadsAutomatically())
        prepareToPlay();
#endif

    configureMediaControls();
}

void HTMLMediaElement::loadInternal()
{
    // Some of the code paths below this function dispatch the BeforeLoad event. This ASSERT helps
    // us catch those bugs more quickly without needing all the branches to align to actually
    // trigger the event.
    ASSERT(!NoEventDispatchAssertion::isEventDispatchForbidden());

    // If we can't start a load right away, start it later.
    if (!m_mediaSession->pageAllowsDataLoading(*this)) {
        setShouldDelayLoadEvent(false);
        if (m_isWaitingUntilMediaCanStart)
            return;
        document().addMediaCanStartListener(this);
        m_isWaitingUntilMediaCanStart = true;
        return;
    }

    clearFlags(m_pendingActionFlags, LoadMediaResource);

    // Once the page has allowed an element to load media, it is free to load at will. This allows a 
    // playlist that starts in a foreground tab to continue automatically if the tab is subsequently 
    // put into the background.
    m_mediaSession->removeBehaviorRestriction(MediaElementSession::RequirePageConsentToLoadMedia);

#if ENABLE(VIDEO_TRACK)
    if (hasMediaControls())
        mediaControls()->changedClosedCaptionsVisibility();

    // HTMLMediaElement::textTracksAreReady will need "... the text tracks whose mode was not in the
    // disabled state when the element's resource selection algorithm last started".
    if (RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled()) {
        m_textTracksWhenResourceSelectionBegan.clear();
        if (m_textTracks) {
            for (unsigned i = 0; i < m_textTracks->length(); ++i) {
                TextTrack* track = m_textTracks->item(i);
                if (track->mode() != TextTrack::disabledKeyword())
                    m_textTracksWhenResourceSelectionBegan.append(track);
            }
        }
    }
#endif

    selectMediaResource();
}

void HTMLMediaElement::selectMediaResource()
{
    LOG(Media, "HTMLMediaElement::selectMediaResource(%p)", this);

    enum Mode { attribute, children };

    // 3 - If the media element has a src attribute, then let mode be attribute.
    Mode mode = attribute;
    if (!fastHasAttribute(srcAttr)) {
        // Otherwise, if the media element does not have a src attribute but has a source 
        // element child, then let mode be children and let candidate be the first such 
        // source element child in tree order.
        if (auto firstSource = childrenOfType<HTMLSourceElement>(*this).first()) {
            mode = children;
            m_nextChildNodeToConsider = firstSource;
            m_currentSourceNode = 0;
        } else {
            // Otherwise the media element has neither a src attribute nor a source element 
            // child: set the networkState to NETWORK_EMPTY, and abort these steps; the 
            // synchronous section ends.
            m_loadState = WaitingForSource;
            setShouldDelayLoadEvent(false);
            m_networkState = NETWORK_EMPTY;

            LOG(Media, "HTMLMediaElement::selectMediaResource(%p) - nothing to load", this);
            return;
        }
    }

    // 4 - Set the media element's delaying-the-load-event flag to true (this delays the load event), 
    // and set its networkState to NETWORK_LOADING.
    setShouldDelayLoadEvent(true);
    m_networkState = NETWORK_LOADING;

    // 5 - Queue a task to fire a simple event named loadstart at the media element.
    scheduleEvent(eventNames().loadstartEvent);

    // 6 - If mode is attribute, then run these substeps
    if (mode == attribute) {
        m_loadState = LoadingFromSrcAttr;

        // If the src attribute's value is the empty string ... jump down to the failed step below
        URL mediaURL = getNonEmptyURLAttribute(srcAttr);
        if (mediaURL.isEmpty()) {
            mediaLoadingFailed(MediaPlayer::FormatError);
            LOG(Media, "HTMLMediaElement::selectMediaResource(%p) -  empty 'src'", this);
            return;
        }

        if (!isSafeToLoadURL(mediaURL, Complain) || !dispatchBeforeLoadEvent(mediaURL.string())) {
            mediaLoadingFailed(MediaPlayer::FormatError);
            return;
        }

        // No type or key system information is available when the url comes
        // from the 'src' attribute so MediaPlayer
        // will have to pick a media engine based on the file extension.
        ContentType contentType((String()));
        loadResource(mediaURL, contentType, String());
        LOG(Media, "HTMLMediaElement::selectMediaResource(%p) - using 'src' attribute url", this);
        return;
    }

    // Otherwise, the source elements will be used
    loadNextSourceChild();
}

void HTMLMediaElement::loadNextSourceChild()
{
    ContentType contentType((String()));
    String keySystem;
    URL mediaURL = selectNextSourceChild(&contentType, &keySystem, Complain);
    if (!mediaURL.isValid()) {
        waitForSourceChange();
        return;
    }

    // Recreate the media player for the new url
    createMediaPlayer();

    m_loadState = LoadingFromSourceElement;
    loadResource(mediaURL, contentType, keySystem);
}

void HTMLMediaElement::loadResource(const URL& initialURL, ContentType& contentType, const String& keySystem)
{
    ASSERT(isSafeToLoadURL(initialURL, Complain));

    LOG(Media, "HTMLMediaElement::loadResource(%p) - %s, %s, %s", this, urlForLoggingMedia(initialURL).utf8().data(), contentType.raw().utf8().data(), keySystem.utf8().data());

    Frame* frame = document().frame();
    if (!frame) {
        mediaLoadingFailed(MediaPlayer::FormatError);
        return;
    }

    Page* page = frame->page();
    if (!page) {
        mediaLoadingFailed(MediaPlayer::FormatError);
        return;
    }

    URL url = initialURL;
    if (!frame->loader().willLoadMediaElementURL(url)) {
        mediaLoadingFailed(MediaPlayer::FormatError);
        return;
    }

#if ENABLE(CONTENT_EXTENSIONS)
    ResourceRequest request(url);
    DocumentLoader* documentLoader = frame->loader().documentLoader();

    if (page->userContentController() && documentLoader)
        page->userContentController()->processContentExtensionRulesForLoad(request, ResourceType::Media, *documentLoader);

    if (request.isNull()) {
        mediaLoadingFailed(MediaPlayer::FormatError);
        return;
    }
#endif

    // The resource fetch algorithm 
    m_networkState = NETWORK_LOADING;

    // If the url should be loaded from the application cache, pass the url of the cached file
    // to the media engine.
    ApplicationCacheHost* cacheHost = frame->loader().documentLoader()->applicationCacheHost();
    ApplicationCacheResource* resource = 0;
    if (cacheHost && cacheHost->shouldLoadResourceFromApplicationCache(ResourceRequest(url), resource)) {
        // Resources that are not present in the manifest will always fail to load (at least, after the
        // cache has been primed the first time), making the testing of offline applications simpler.
        if (!resource || resource->path().isEmpty()) {
            mediaLoadingFailed(MediaPlayer::NetworkError);
            return;
        }
    }

    // Log that we started loading a media element.
    if (Frame* frame = document().frame())
        frame->mainFrame().diagnosticLoggingClient().logDiagnosticMessageWithValue(DiagnosticLoggingKeys::mediaKey(), isVideo() ? DiagnosticLoggingKeys::videoKey() : DiagnosticLoggingKeys::audioKey(), DiagnosticLoggingKeys::loadingKey(), ShouldSample::No);

    m_firstTimePlaying = true;

    // Set m_currentSrc *before* changing to the cache url, the fact that we are loading from the app
    // cache is an internal detail not exposed through the media element API.
    m_currentSrc = url;

    if (resource) {
        url = ApplicationCacheHost::createFileURL(resource->path());
        LOG(Media, "HTMLMediaElement::loadResource(%p) - will load from app cache -> %s", this, urlForLoggingMedia(url).utf8().data());
    }

    LOG(Media, "HTMLMediaElement::loadResource(%p) - m_currentSrc -> %s", this, urlForLoggingMedia(m_currentSrc).utf8().data());

#if ENABLE(MEDIA_STREAM)
    if (MediaStreamRegistry::registry().lookup(url.string()))
        m_mediaSession->removeBehaviorRestriction(MediaElementSession::RequireUserGestureForRateChange);
#endif

    if (m_sendProgressEvents) 
        startProgressEventTimer();

    bool privateMode = document().page() && document().page()->usesEphemeralSession();
    m_player->setPrivateBrowsingMode(privateMode);

    // Reset display mode to force a recalculation of what to show because we are resetting the player.
    setDisplayMode(Unknown);

    if (!autoplay())
        m_player->setPreload(m_mediaSession->effectivePreloadForElement(*this));
    m_player->setPreservesPitch(m_webkitPreservesPitch);

    if (!m_explicitlyMuted) {
        m_explicitlyMuted = true;
        m_muted = fastHasAttribute(mutedAttr);
    }

    updateVolume();

#if ENABLE(MEDIA_SOURCE)
    ASSERT(!m_mediaSource);

    if (url.protocolIs(mediaSourceBlobProtocol))
        m_mediaSource = MediaSource::lookup(url.string());

    if (m_mediaSource) {
        if (m_mediaSource->attachToElement(this))
            m_player->load(url, contentType, m_mediaSource.get());
        else {
            // Forget our reference to the MediaSource, so we leave it alone
            // while processing remainder of load failure.
            m_mediaSource = 0;
            mediaLoadingFailed(MediaPlayer::FormatError);
        }
    } else
#endif
#if ENABLE(MEDIA_STREAM)
        if (m_mediaStreamSrcObject)
            m_player->load(m_mediaStreamSrcObject->privateStream());
        else
#endif
    if (!m_player->load(url, contentType, keySystem))
        mediaLoadingFailed(MediaPlayer::FormatError);

    // If there is no poster to display, allow the media engine to render video frames as soon as
    // they are available.
    updateDisplayState();

    if (renderer())
        renderer()->updateFromElement();
}

#if ENABLE(VIDEO_TRACK)
static bool trackIndexCompare(TextTrack* a,
                              TextTrack* b)
{
    return a->trackIndex() - b->trackIndex() < 0;
}

static bool eventTimeCueCompare(const std::pair<MediaTime, TextTrackCue*>& a, const std::pair<MediaTime, TextTrackCue*>& b)
{
    // 12 - Sort the tasks in events in ascending time order (tasks with earlier
    // times first).
    if (a.first != b.first)
        return a.first - b.first < MediaTime::zeroTime();

    // If the cues belong to different text tracks, it doesn't make sense to
    // compare the two tracks by the relative cue order, so return the relative
    // track order.
    if (a.second->track() != b.second->track())
        return trackIndexCompare(a.second->track(), b.second->track());

    // 12 - Further sort tasks in events that have the same time by the
    // relative text track cue order of the text track cues associated
    // with these tasks.
    return a.second->cueIndex() - b.second->cueIndex() < 0;
}

static bool compareCueInterval(const CueInterval& one, const CueInterval& two)
{
    return one.data()->isOrderedBefore(two.data());
};


void HTMLMediaElement::updateActiveTextTrackCues(const MediaTime& movieTime)
{
    // 4.8.10.8 Playing the media resource

    //  If the current playback position changes while the steps are running,
    //  then the user agent must wait for the steps to complete, and then must
    //  immediately rerun the steps.
    if (ignoreTrackDisplayUpdateRequests())
        return;

    LOG(Media, "HTMLMediaElement::updateActiveTextTracks(%p)", this);

    // 1 - Let current cues be a list of cues, initialized to contain all the
    // cues of all the hidden, showing, or showing by default text tracks of the
    // media element (not the disabled ones) whose start times are less than or
    // equal to the current playback position and whose end times are greater
    // than the current playback position.
    CueList currentCues;

    // The user agent must synchronously unset [the text track cue active] flag
    // whenever ... the media element's readyState is changed back to HAVE_NOTHING.
    if (m_readyState != HAVE_NOTHING && m_player) {
        currentCues = m_cueTree.allOverlaps(m_cueTree.createInterval(movieTime, movieTime));
        if (currentCues.size() > 1)
            std::sort(currentCues.begin(), currentCues.end(), &compareCueInterval);
    }

    CueList previousCues;
    CueList missedCues;

    // 2 - Let other cues be a list of cues, initialized to contain all the cues
    // of hidden, showing, and showing by default text tracks of the media
    // element that are not present in current cues.
    previousCues = m_currentlyActiveCues;

    // 3 - Let last time be the current playback position at the time this
    // algorithm was last run for this media element, if this is not the first
    // time it has run.
    MediaTime lastTime = m_lastTextTrackUpdateTime;

    // 4 - If the current playback position has, since the last time this
    // algorithm was run, only changed through its usual monotonic increase
    // during normal playback, then let missed cues be the list of cues in other
    // cues whose start times are greater than or equal to last time and whose
    // end times are less than or equal to the current playback position.
    // Otherwise, let missed cues be an empty list.
    if (lastTime >= MediaTime::zeroTime() && m_lastSeekTime < movieTime) {
        CueList potentiallySkippedCues =
            m_cueTree.allOverlaps(m_cueTree.createInterval(lastTime, movieTime));

        for (size_t i = 0; i < potentiallySkippedCues.size(); ++i) {
            MediaTime cueStartTime = potentiallySkippedCues[i].low();
            MediaTime cueEndTime = potentiallySkippedCues[i].high();

            // Consider cues that may have been missed since the last seek time.
            if (cueStartTime > std::max(m_lastSeekTime, lastTime) && cueEndTime < movieTime)
                missedCues.append(potentiallySkippedCues[i]);
        }
    }

    m_lastTextTrackUpdateTime = movieTime;

    // 5 - If the time was reached through the usual monotonic increase of the
    // current playback position during normal playback, and if the user agent
    // has not fired a timeupdate event at the element in the past 15 to 250ms
    // and is not still running event handlers for such an event, then the user
    // agent must queue a task to fire a simple event named timeupdate at the
    // element. (In the other cases, such as explicit seeks, relevant events get
    // fired as part of the overall process of changing the current playback
    // position.)
    if (!m_paused && m_lastSeekTime <= lastTime)
        scheduleTimeupdateEvent(false);

    // Explicitly cache vector sizes, as their content is constant from here.
    size_t currentCuesSize = currentCues.size();
    size_t missedCuesSize = missedCues.size();
    size_t previousCuesSize = previousCues.size();

    // 6 - If all of the cues in current cues have their text track cue active
    // flag set, none of the cues in other cues have their text track cue active
    // flag set, and missed cues is empty, then abort these steps.
    bool activeSetChanged = missedCuesSize;

    for (size_t i = 0; !activeSetChanged && i < previousCuesSize; ++i)
        if (!currentCues.contains(previousCues[i]) && previousCues[i].data()->isActive())
            activeSetChanged = true;

    for (size_t i = 0; i < currentCuesSize; ++i) {
        TextTrackCue* cue = currentCues[i].data();

        if (cue->isRenderable())
            toVTTCue(cue)->updateDisplayTree(movieTime);

        if (!cue->isActive())
            activeSetChanged = true;
    }

    if (!activeSetChanged)
        return;

    // 7 - If the time was reached through the usual monotonic increase of the
    // current playback position during normal playback, and there are cues in
    // other cues that have their text track cue pause-on-exi flag set and that
    // either have their text track cue active flag set or are also in missed
    // cues, then immediately pause the media element.
    for (size_t i = 0; !m_paused && i < previousCuesSize; ++i) {
        if (previousCues[i].data()->pauseOnExit()
            && previousCues[i].data()->isActive()
            && !currentCues.contains(previousCues[i]))
            pause();
    }

    for (size_t i = 0; !m_paused && i < missedCuesSize; ++i) {
        if (missedCues[i].data()->pauseOnExit())
            pause();
    }

    // 8 - Let events be a list of tasks, initially empty. Each task in this
    // list will be associated with a text track, a text track cue, and a time,
    // which are used to sort the list before the tasks are queued.
    Vector<std::pair<MediaTime, TextTrackCue*>> eventTasks;

    // 8 - Let affected tracks be a list of text tracks, initially empty.
    Vector<TextTrack*> affectedTracks;

    for (size_t i = 0; i < missedCuesSize; ++i) {
        // 9 - For each text track cue in missed cues, prepare an event named enter
        // for the TextTrackCue object with the text track cue start time.
        eventTasks.append(std::make_pair(missedCues[i].data()->startMediaTime(),
                                         missedCues[i].data()));

        // 10 - For each text track [...] in missed cues, prepare an event
        // named exit for the TextTrackCue object with the  with the later of
        // the text track cue end time and the text track cue start time.

        // Note: An explicit task is added only if the cue is NOT a zero or
        // negative length cue. Otherwise, the need for an exit event is
        // checked when these tasks are actually queued below. This doesn't
        // affect sorting events before dispatch either, because the exit
        // event has the same time as the enter event.
        if (missedCues[i].data()->startMediaTime() < missedCues[i].data()->endMediaTime())
            eventTasks.append(std::make_pair(missedCues[i].data()->endMediaTime(), missedCues[i].data()));
    }

    for (size_t i = 0; i < previousCuesSize; ++i) {
        // 10 - For each text track cue in other cues that has its text
        // track cue active flag set prepare an event named exit for the
        // TextTrackCue object with the text track cue end time.
        if (!currentCues.contains(previousCues[i]))
            eventTasks.append(std::make_pair(previousCues[i].data()->endMediaTime(),
                                             previousCues[i].data()));
    }

    for (size_t i = 0; i < currentCuesSize; ++i) {
        // 11 - For each text track cue in current cues that does not have its
        // text track cue active flag set, prepare an event named enter for the
        // TextTrackCue object with the text track cue start time.
        if (!previousCues.contains(currentCues[i]))
            eventTasks.append(std::make_pair(currentCues[i].data()->startMediaTime(),
                                             currentCues[i].data()));
    }

    // 12 - Sort the tasks in events in ascending time order (tasks with earlier
    // times first).
    std::sort(eventTasks.begin(), eventTasks.end(), eventTimeCueCompare);

    for (size_t i = 0; i < eventTasks.size(); ++i) {
        if (!affectedTracks.contains(eventTasks[i].second->track()))
            affectedTracks.append(eventTasks[i].second->track());

        // 13 - Queue each task in events, in list order.
        RefPtr<Event> event;

        // Each event in eventTasks may be either an enterEvent or an exitEvent,
        // depending on the time that is associated with the event. This
        // correctly identifies the type of the event, if the startTime is
        // less than the endTime in the cue.
        if (eventTasks[i].second->startTime() >= eventTasks[i].second->endTime()) {
            event = Event::create(eventNames().enterEvent, false, false);
            event->setTarget(eventTasks[i].second);
            m_asyncEventQueue.enqueueEvent(event.release());

            event = Event::create(eventNames().exitEvent, false, false);
            event->setTarget(eventTasks[i].second);
            m_asyncEventQueue.enqueueEvent(event.release());
        } else {
            if (eventTasks[i].first == eventTasks[i].second->startMediaTime())
                event = Event::create(eventNames().enterEvent, false, false);
            else
                event = Event::create(eventNames().exitEvent, false, false);

            event->setTarget(eventTasks[i].second);
            m_asyncEventQueue.enqueueEvent(event.release());
        }
    }

    // 14 - Sort affected tracks in the same order as the text tracks appear in
    // the media element's list of text tracks, and remove duplicates.
    std::sort(affectedTracks.begin(), affectedTracks.end(), trackIndexCompare);

    // 15 - For each text track in affected tracks, in the list order, queue a
    // task to fire a simple event named cuechange at the TextTrack object, and, ...
    for (size_t i = 0; i < affectedTracks.size(); ++i) {
        RefPtr<Event> event = Event::create(eventNames().cuechangeEvent, false, false);
        event->setTarget(affectedTracks[i]);

        m_asyncEventQueue.enqueueEvent(event.release());

        // ... if the text track has a corresponding track element, to then fire a
        // simple event named cuechange at the track element as well.
        if (is<LoadableTextTrack>(*affectedTracks[i])) {
            RefPtr<Event> event = Event::create(eventNames().cuechangeEvent, false, false);
            HTMLTrackElement* trackElement = downcast<LoadableTextTrack>(*affectedTracks[i]).trackElement();
            ASSERT(trackElement);
            event->setTarget(trackElement);
            
            m_asyncEventQueue.enqueueEvent(event.release());
        }
    }

    // 16 - Set the text track cue active flag of all the cues in the current
    // cues, and unset the text track cue active flag of all the cues in the
    // other cues.
    for (size_t i = 0; i < currentCuesSize; ++i)
        currentCues[i].data()->setIsActive(true);

    for (size_t i = 0; i < previousCuesSize; ++i)
        if (!currentCues.contains(previousCues[i]))
            previousCues[i].data()->setIsActive(false);

    // Update the current active cues.
    m_currentlyActiveCues = currentCues;

    if (activeSetChanged)
        updateTextTrackDisplay();
}

bool HTMLMediaElement::textTracksAreReady() const
{
    // 4.8.10.12.1 Text track model
    // ...
    // The text tracks of a media element are ready if all the text tracks whose mode was not 
    // in the disabled state when the element's resource selection algorithm last started now
    // have a text track readiness state of loaded or failed to load.
    for (unsigned i = 0; i < m_textTracksWhenResourceSelectionBegan.size(); ++i) {
        if (m_textTracksWhenResourceSelectionBegan[i]->readinessState() == TextTrack::Loading
            || m_textTracksWhenResourceSelectionBegan[i]->readinessState() == TextTrack::NotLoaded)
            return false;
    }

    return true;
}

void HTMLMediaElement::textTrackReadyStateChanged(TextTrack* track)
{
    if (m_player && m_textTracksWhenResourceSelectionBegan.contains(track)) {
        if (track->readinessState() != TextTrack::Loading)
            setReadyState(m_player->readyState());
    } else {
        // The track readiness state might have changed as a result of the user
        // clicking the captions button. In this case, a check whether all the
        // resources have failed loading should be done in order to hide the CC button.
        if (hasMediaControls() && track->readinessState() == TextTrack::FailedToLoad)
            mediaControls()->refreshClosedCaptionsButtonVisibility();
    }
}

void HTMLMediaElement::audioTrackEnabledChanged(AudioTrack* track)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;
    if (m_audioTracks && m_audioTracks->contains(track))
        m_audioTracks->scheduleChangeEvent();
}

void HTMLMediaElement::textTrackModeChanged(TextTrack* track)
{
    bool trackIsLoaded = true;
    if (track->trackType() == TextTrack::TrackElement) {
        trackIsLoaded = false;
        for (auto& trackElement : childrenOfType<HTMLTrackElement>(*this)) {
            if (trackElement.track() == track) {
                if (trackElement.readyState() == HTMLTrackElement::LOADING || trackElement.readyState() == HTMLTrackElement::LOADED)
                    trackIsLoaded = true;
                break;
            }
        }
    }

    // If this is the first added track, create the list of text tracks.
    if (!m_textTracks)
        m_textTracks = TextTrackList::create(this, ActiveDOMObject::scriptExecutionContext());
    
    // Mark this track as "configured" so configureTextTracks won't change the mode again.
    track->setHasBeenConfigured(true);
    
    if (track->mode() != TextTrack::disabledKeyword() && trackIsLoaded)
        textTrackAddCues(track, track->cues());

#if USE(PLATFORM_TEXT_TRACK_MENU)
    if (platformTextTrackMenu())
        platformTextTrackMenu()->trackWasSelected(track->platformTextTrack());
#endif
    
    configureTextTrackDisplay(AssumeTextTrackVisibilityChanged);

    if (m_textTracks && m_textTracks->contains(track))
        m_textTracks->scheduleChangeEvent();

#if ENABLE(AVF_CAPTIONS)
    if (track->trackType() == TextTrack::TrackElement && m_player)
        m_player->notifyTrackModeChanged();
#endif
}

void HTMLMediaElement::videoTrackSelectedChanged(VideoTrack* track)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;
    if (m_videoTracks && m_videoTracks->contains(track))
        m_videoTracks->scheduleChangeEvent();
}

void HTMLMediaElement::textTrackKindChanged(TextTrack* track)
{
    if (track->kind() != TextTrack::captionsKeyword() && track->kind() != TextTrack::subtitlesKeyword() && track->mode() == TextTrack::showingKeyword())
        track->setMode(TextTrack::hiddenKeyword());
}

void HTMLMediaElement::beginIgnoringTrackDisplayUpdateRequests()
{
    ++m_ignoreTrackDisplayUpdate;
}

void HTMLMediaElement::endIgnoringTrackDisplayUpdateRequests()
{
    ASSERT(m_ignoreTrackDisplayUpdate);
    --m_ignoreTrackDisplayUpdate;
    if (!m_ignoreTrackDisplayUpdate && m_inActiveDocument)
        updateActiveTextTrackCues(currentMediaTime());
}

void HTMLMediaElement::textTrackAddCues(TextTrack* track, const TextTrackCueList* cues) 
{
    if (track->mode() == TextTrack::disabledKeyword())
        return;

    TrackDisplayUpdateScope scope(this);
    for (size_t i = 0; i < cues->length(); ++i)
        textTrackAddCue(track, cues->item(i));
}

void HTMLMediaElement::textTrackRemoveCues(TextTrack*, const TextTrackCueList* cues) 
{
    TrackDisplayUpdateScope scope(this);
    for (size_t i = 0; i < cues->length(); ++i)
        textTrackRemoveCue(cues->item(i)->track(), cues->item(i));
}

void HTMLMediaElement::textTrackAddCue(TextTrack* track, PassRefPtr<TextTrackCue> prpCue)
{
    if (track->mode() == TextTrack::disabledKeyword())
        return;

    RefPtr<TextTrackCue> cue = prpCue;

    // Negative duration cues need be treated in the interval tree as
    // zero-length cues.
    MediaTime endTime = std::max(cue->startMediaTime(), cue->endMediaTime());

    CueInterval interval = m_cueTree.createInterval(cue->startMediaTime(), endTime, cue.get());
    if (!m_cueTree.contains(interval))
        m_cueTree.add(interval);
    updateActiveTextTrackCues(currentMediaTime());
}

void HTMLMediaElement::textTrackRemoveCue(TextTrack*, PassRefPtr<TextTrackCue> prpCue)
{
    RefPtr<TextTrackCue> cue = prpCue;
    // Negative duration cues need to be treated in the interval tree as
    // zero-length cues.
    MediaTime endTime = std::max(cue->startMediaTime(), cue->endMediaTime());

    CueInterval interval = m_cueTree.createInterval(cue->startMediaTime(), endTime, cue.get());
    m_cueTree.remove(interval);

#if ENABLE(WEBVTT_REGIONS)
    // Since the cue will be removed from the media element and likely the
    // TextTrack might also be destructed, notifying the region of the cue
    // removal shouldn't be done.
    if (cue->isRenderable())
        toVTTCue(cue.get())->notifyRegionWhenRemovingDisplayTree(false);
#endif

    size_t index = m_currentlyActiveCues.find(interval);
    if (index != notFound) {
        cue->setIsActive(false);
        m_currentlyActiveCues.remove(index);
    }

    if (cue->isRenderable())
        toVTTCue(cue.get())->removeDisplayTree();
    updateActiveTextTrackCues(currentMediaTime());

#if ENABLE(WEBVTT_REGIONS)
    if (cue->isRenderable())
        toVTTCue(cue.get())->notifyRegionWhenRemovingDisplayTree(true);
#endif
}

#endif

bool HTMLMediaElement::isSafeToLoadURL(const URL& url, InvalidURLAction actionIfInvalid)
{
    if (!url.isValid()) {
        LOG(Media, "HTMLMediaElement::isSafeToLoadURL(%p) - %s -> FALSE because url is invalid", this, urlForLoggingMedia(url).utf8().data());
        return false;
    }

    Frame* frame = document().frame();
    if (!frame || !document().securityOrigin()->canDisplay(url)) {
        if (actionIfInvalid == Complain)
            FrameLoader::reportLocalLoadFailed(frame, url.stringCenterEllipsizedToLength());
        LOG(Media, "HTMLMediaElement::isSafeToLoadURL(%p) - %s -> FALSE rejected by SecurityOrigin", this, urlForLoggingMedia(url).utf8().data());
        return false;
    }

    if (!document().contentSecurityPolicy()->allowMediaFromSource(url)) {
        LOG(Media, "HTMLMediaElement::isSafeToLoadURL(%p) - %s -> rejected by Content Security Policy", this, urlForLoggingMedia(url).utf8().data());
        return false;
    }

    return true;
}

void HTMLMediaElement::startProgressEventTimer()
{
    if (m_progressEventTimer.isActive())
        return;

    m_previousProgressTime = monotonicallyIncreasingTime();
    // 350ms is not magic, it is in the spec!
    m_progressEventTimer.startRepeating(0.350);
}

void HTMLMediaElement::waitForSourceChange()
{
    LOG(Media, "HTMLMediaElement::waitForSourceChange(%p)", this);

    stopPeriodicTimers();
    m_loadState = WaitingForSource;

    // 6.17 - Waiting: Set the element's networkState attribute to the NETWORK_NO_SOURCE value
    m_networkState = NETWORK_NO_SOURCE;

    // 6.18 - Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
    setShouldDelayLoadEvent(false);

    updateDisplayState();

    if (renderer())
        renderer()->updateFromElement();
}

void HTMLMediaElement::noneSupported()
{
    LOG(Media, "HTMLMediaElement::noneSupported(%p)", this);

    stopPeriodicTimers();
    m_loadState = WaitingForSource;
    m_currentSourceNode = 0;

    // 4.8.10.5 
    // 6 - Reaching this step indicates that the media resource failed to load or that the given 
    // URL could not be resolved. In one atomic operation, run the following steps:

    // 6.1 - Set the error attribute to a new MediaError object whose code attribute is set to
    // MEDIA_ERR_SRC_NOT_SUPPORTED.
    m_error = MediaError::create(MediaError::MEDIA_ERR_SRC_NOT_SUPPORTED);

    // 6.2 - Forget the media element's media-resource-specific text tracks.
    forgetResourceSpecificTracks();

    // 6.3 - Set the element's networkState attribute to the NETWORK_NO_SOURCE value.
    m_networkState = NETWORK_NO_SOURCE;

    // 7 - Queue a task to fire a simple event named error at the media element.
    scheduleEvent(eventNames().errorEvent);

#if ENABLE(MEDIA_SOURCE)
    closeMediaSource();
#endif

    // 8 - Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
    setShouldDelayLoadEvent(false);

    // 9 - Abort these steps. Until the load() method is invoked or the src attribute is changed, 
    // the element won't attempt to load another resource.

    updateDisplayState();

    if (renderer())
        renderer()->updateFromElement();
}

void HTMLMediaElement::mediaLoadingFailedFatally(MediaPlayer::NetworkState error)
{
    LOG(Media, "HTMLMediaElement::mediaLoadingFailedFatally(%p) - error = %d", this, static_cast<int>(error));

    // 1 - The user agent should cancel the fetching process.
    stopPeriodicTimers();
    m_loadState = WaitingForSource;

    // 2 - Set the error attribute to a new MediaError object whose code attribute is 
    // set to MEDIA_ERR_NETWORK/MEDIA_ERR_DECODE.
    if (error == MediaPlayer::NetworkError)
        m_error = MediaError::create(MediaError::MEDIA_ERR_NETWORK);
    else if (error == MediaPlayer::DecodeError)
        m_error = MediaError::create(MediaError::MEDIA_ERR_DECODE);
    else
        ASSERT_NOT_REACHED();

    // 3 - Queue a task to fire a simple event named error at the media element.
    scheduleEvent(eventNames().errorEvent);

#if ENABLE(MEDIA_SOURCE)
    closeMediaSource();
#endif

    // 4 - Set the element's networkState attribute to the NETWORK_EMPTY value and queue a
    // task to fire a simple event called emptied at the element.
    m_networkState = NETWORK_EMPTY;
    scheduleEvent(eventNames().emptiedEvent);

    // 5 - Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
    setShouldDelayLoadEvent(false);

    // 6 - Abort the overall resource selection algorithm.
    m_currentSourceNode = nullptr;

#if PLATFORM(COCOA)
    if (is<MediaDocument>(document()))
        downcast<MediaDocument>(document()).mediaElementSawUnsupportedTracks();
#endif
}

void HTMLMediaElement::cancelPendingEventsAndCallbacks()
{
    LOG(Media, "HTMLMediaElement::cancelPendingEventsAndCallbacks(%p)", this);
    m_asyncEventQueue.cancelAllEvents();

    for (auto& source : childrenOfType<HTMLSourceElement>(*this))
        source.cancelPendingErrorEvent();
}

void HTMLMediaElement::mediaPlayerNetworkStateChanged(MediaPlayer*)
{
    beginProcessingMediaPlayerCallback();
    setNetworkState(m_player->networkState());
    endProcessingMediaPlayerCallback();
}

static void logMediaLoadRequest(Page* page, const String& mediaEngine, const String& errorMessage, bool succeeded)
{
    if (!page)
        return;

    DiagnosticLoggingClient& diagnosticLoggingClient = page->mainFrame().diagnosticLoggingClient();
    if (!succeeded) {
        diagnosticLoggingClient.logDiagnosticMessageWithResult(DiagnosticLoggingKeys::mediaLoadingFailedKey(), errorMessage, DiagnosticLoggingResultFail, ShouldSample::No);
        return;
    }

    diagnosticLoggingClient.logDiagnosticMessage(DiagnosticLoggingKeys::mediaLoadedKey(), mediaEngine, ShouldSample::No);

    if (!page->hasSeenAnyMediaEngine())
        diagnosticLoggingClient.logDiagnosticMessage(DiagnosticLoggingKeys::pageContainsAtLeastOneMediaEngineKey(), emptyString(), ShouldSample::No);

    if (!page->hasSeenMediaEngine(mediaEngine))
        diagnosticLoggingClient.logDiagnosticMessage(DiagnosticLoggingKeys::pageContainsMediaEngineKey(), mediaEngine, ShouldSample::No);

    page->sawMediaEngine(mediaEngine);
}

static String stringForNetworkState(MediaPlayer::NetworkState state)
{
    switch (state) {
    case MediaPlayer::Empty: return ASCIILiteral("Empty");
    case MediaPlayer::Idle: return ASCIILiteral("Idle");
    case MediaPlayer::Loading: return ASCIILiteral("Loading");
    case MediaPlayer::Loaded: return ASCIILiteral("Loaded");
    case MediaPlayer::FormatError: return ASCIILiteral("FormatError");
    case MediaPlayer::NetworkError: return ASCIILiteral("NetworkError");
    case MediaPlayer::DecodeError: return ASCIILiteral("DecodeError");
    default: return emptyString();
    }
}

void HTMLMediaElement::mediaLoadingFailed(MediaPlayer::NetworkState error)
{
    stopPeriodicTimers();
    
    // If we failed while trying to load a <source> element, the movie was never parsed, and there are more
    // <source> children, schedule the next one
    if (m_readyState < HAVE_METADATA && m_loadState == LoadingFromSourceElement) {
        
        // resource selection algorithm
        // Step 9.Otherwise.9 - Failed with elements: Queue a task, using the DOM manipulation task source, to fire a simple event named error at the candidate element.
        if (m_currentSourceNode)
            m_currentSourceNode->scheduleErrorEvent();
        else
            LOG(Media, "HTMLMediaElement::setNetworkState(%p) - error event not sent, <source> was removed", this);
        
        // 9.Otherwise.10 - Asynchronously await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended.
        
        // 9.Otherwise.11 - Forget the media element's media-resource-specific tracks.
        forgetResourceSpecificTracks();

        if (havePotentialSourceChild()) {
            LOG(Media, "HTMLMediaElement::setNetworkState(%p) - scheduling next <source>", this);
            scheduleNextSourceChild();
        } else {
            LOG(Media, "HTMLMediaElement::setNetworkState(%p) - no more <source> elements, waiting", this);
            waitForSourceChange();
        }
        
        return;
    }
    
    if ((error == MediaPlayer::NetworkError && m_readyState >= HAVE_METADATA) || error == MediaPlayer::DecodeError)
        mediaLoadingFailedFatally(error);
    else if ((error == MediaPlayer::FormatError || error == MediaPlayer::NetworkError) && m_loadState == LoadingFromSrcAttr)
        noneSupported();
    
    updateDisplayState();
    if (hasMediaControls()) {
        mediaControls()->reset();
        mediaControls()->reportedError();
    }

    logMediaLoadRequest(document().page(), String(), stringForNetworkState(error), false);
}

void HTMLMediaElement::setNetworkState(MediaPlayer::NetworkState state)
{
    LOG(Media, "HTMLMediaElement::setNetworkState(%p) - new state = %d, current state = %d", this, static_cast<int>(state), static_cast<int>(m_networkState));

    if (state == MediaPlayer::Empty) {
        // Just update the cached state and leave, we can't do anything.
        m_networkState = NETWORK_EMPTY;
        return;
    }

    if (state == MediaPlayer::FormatError || state == MediaPlayer::NetworkError || state == MediaPlayer::DecodeError) {
        mediaLoadingFailed(state);
        return;
    }

    if (state == MediaPlayer::Idle) {
        if (m_networkState > NETWORK_IDLE) {
            changeNetworkStateFromLoadingToIdle();
            setShouldDelayLoadEvent(false);
        } else {
            m_networkState = NETWORK_IDLE;
        }
    }

    if (state == MediaPlayer::Loading) {
        if (m_networkState < NETWORK_LOADING || m_networkState == NETWORK_NO_SOURCE)
            startProgressEventTimer();
        m_networkState = NETWORK_LOADING;
    }

    if (state == MediaPlayer::Loaded) {
        if (m_networkState != NETWORK_IDLE)
            changeNetworkStateFromLoadingToIdle();
        m_completelyLoaded = true;
    }

    if (hasMediaControls())
        mediaControls()->updateStatusDisplay();
}

void HTMLMediaElement::changeNetworkStateFromLoadingToIdle()
{
    m_progressEventTimer.stop();
    if (hasMediaControls() && m_player->didLoadingProgress())
        mediaControls()->bufferingProgressed();

    // Schedule one last progress event so we guarantee that at least one is fired
    // for files that load very quickly.
    scheduleEvent(eventNames().progressEvent);
    scheduleEvent(eventNames().suspendEvent);
    m_networkState = NETWORK_IDLE;
}

void HTMLMediaElement::mediaPlayerReadyStateChanged(MediaPlayer*)
{
    beginProcessingMediaPlayerCallback();

    setReadyState(m_player->readyState());

    endProcessingMediaPlayerCallback();
}

void HTMLMediaElement::setReadyState(MediaPlayer::ReadyState state)
{
    LOG(Media, "HTMLMediaElement::setReadyState(%p) - new state = %d, current state = %d,", this, static_cast<int>(state), static_cast<int>(m_readyState));

    // Set "wasPotentiallyPlaying" BEFORE updating m_readyState, potentiallyPlaying() uses it
    bool wasPotentiallyPlaying = potentiallyPlaying();

    ReadyState oldState = m_readyState;
    ReadyState newState = static_cast<ReadyState>(state);

#if ENABLE(VIDEO_TRACK)
    bool tracksAreReady = !RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled() || textTracksAreReady();

    if (newState == oldState && m_tracksAreReady == tracksAreReady)
        return;

    m_tracksAreReady = tracksAreReady;
#else
    if (newState == oldState)
        return;
    bool tracksAreReady = true;
#endif
    
    if (tracksAreReady)
        m_readyState = newState;
    else {
        // If a media file has text tracks the readyState may not progress beyond HAVE_FUTURE_DATA until
        // the text tracks are ready, regardless of the state of the media file.
        if (newState <= HAVE_METADATA)
            m_readyState = newState;
        else
            m_readyState = HAVE_CURRENT_DATA;
    }
    
    if (oldState > m_readyStateMaximum)
        m_readyStateMaximum = oldState;

    if (m_networkState == NETWORK_EMPTY)
        return;

    if (m_seeking) {
        // 4.8.10.9, step 11
        if (wasPotentiallyPlaying && m_readyState < HAVE_FUTURE_DATA)
            scheduleEvent(eventNames().waitingEvent);

        // 4.8.10.10 step 14 & 15.
        if (!m_player->seeking() && m_readyState >= HAVE_CURRENT_DATA)
            finishSeek();
    } else {
        if (wasPotentiallyPlaying && m_readyState < HAVE_FUTURE_DATA) {
            // 4.8.10.8
            invalidateCachedTime();
            scheduleTimeupdateEvent(false);
            scheduleEvent(eventNames().waitingEvent);
        }
    }

    if (m_readyState >= HAVE_METADATA && oldState < HAVE_METADATA) {
        prepareMediaFragmentURI();
        scheduleEvent(eventNames().durationchangeEvent);
        scheduleEvent(eventNames().loadedmetadataEvent);
#if ENABLE(WIRELESS_PLAYBACK_TARGET)
        if (hasEventListeners(eventNames().webkitplaybacktargetavailabilitychangedEvent))
            enqueuePlaybackTargetAvailabilityChangedEvent();
#endif
        
        if (hasMediaControls())
            mediaControls()->loadedMetadata();
        if (renderer())
            renderer()->updateFromElement();

        logMediaLoadRequest(document().page(), m_player->engineDescription(), String(), true);
    }

    bool shouldUpdateDisplayState = false;

    if (m_readyState >= HAVE_CURRENT_DATA && oldState < HAVE_CURRENT_DATA && !m_haveFiredLoadedData) {
        m_haveFiredLoadedData = true;
        shouldUpdateDisplayState = true;
        scheduleEvent(eventNames().loadeddataEvent);
        setShouldDelayLoadEvent(false);
        applyMediaFragmentURI();
    }

    bool isPotentiallyPlaying = potentiallyPlaying();
    if (m_readyState == HAVE_FUTURE_DATA && oldState <= HAVE_CURRENT_DATA && tracksAreReady) {
        scheduleEvent(eventNames().canplayEvent);
        if (isPotentiallyPlaying)
            scheduleEvent(eventNames().playingEvent);
        shouldUpdateDisplayState = true;
    }

    if (m_readyState == HAVE_ENOUGH_DATA && oldState < HAVE_ENOUGH_DATA && tracksAreReady) {
        if (oldState <= HAVE_CURRENT_DATA)
            scheduleEvent(eventNames().canplayEvent);

        scheduleEvent(eventNames().canplaythroughEvent);

        if (isPotentiallyPlaying && oldState <= HAVE_CURRENT_DATA)
            scheduleEvent(eventNames().playingEvent);

        if (m_autoplaying && m_paused && autoplay() && !document().isSandboxed(SandboxAutomaticFeatures) && m_mediaSession->playbackPermitted(*this)) {
            m_paused = false;
            invalidateCachedTime();
            scheduleEvent(eventNames().playEvent);
            scheduleEvent(eventNames().playingEvent);
        }

        shouldUpdateDisplayState = true;
    }

    if (shouldUpdateDisplayState) {
        updateDisplayState();
        if (hasMediaControls()) {
            mediaControls()->refreshClosedCaptionsButtonVisibility();
            mediaControls()->updateStatusDisplay();
        }
    }

    updatePlayState();
    updateMediaController();
#if ENABLE(VIDEO_TRACK)
    if (RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        updateActiveTextTrackCues(currentMediaTime());
#endif
}

#if ENABLE(ENCRYPTED_MEDIA)
void HTMLMediaElement::mediaPlayerKeyAdded(MediaPlayer*, const String& keySystem, const String& sessionId)
{
    MediaKeyEventInit initializer;
    initializer.keySystem = keySystem;
    initializer.sessionId = sessionId;
    initializer.bubbles = false;
    initializer.cancelable = false;

    RefPtr<Event> event = MediaKeyEvent::create(eventNames().webkitkeyaddedEvent, initializer);
    event->setTarget(this);
    m_asyncEventQueue.enqueueEvent(event.release());
}

void HTMLMediaElement::mediaPlayerKeyError(MediaPlayer*, const String& keySystem, const String& sessionId, MediaPlayerClient::MediaKeyErrorCode errorCode, unsigned short systemCode)
{
    MediaKeyError::Code mediaKeyErrorCode = MediaKeyError::MEDIA_KEYERR_UNKNOWN;
    switch (errorCode) {
    case MediaPlayerClient::UnknownError:
        mediaKeyErrorCode = MediaKeyError::MEDIA_KEYERR_UNKNOWN;
        break;
    case MediaPlayerClient::ClientError:
        mediaKeyErrorCode = MediaKeyError::MEDIA_KEYERR_CLIENT;
        break;
    case MediaPlayerClient::ServiceError:
        mediaKeyErrorCode = MediaKeyError::MEDIA_KEYERR_SERVICE;
        break;
    case MediaPlayerClient::OutputError:
        mediaKeyErrorCode = MediaKeyError::MEDIA_KEYERR_OUTPUT;
        break;
    case MediaPlayerClient::HardwareChangeError:
        mediaKeyErrorCode = MediaKeyError::MEDIA_KEYERR_HARDWARECHANGE;
        break;
    case MediaPlayerClient::DomainError:
        mediaKeyErrorCode = MediaKeyError::MEDIA_KEYERR_DOMAIN;
        break;
    }

    MediaKeyEventInit initializer;
    initializer.keySystem = keySystem;
    initializer.sessionId = sessionId;
    initializer.errorCode = MediaKeyError::create(mediaKeyErrorCode);
    initializer.systemCode = systemCode;
    initializer.bubbles = false;
    initializer.cancelable = false;

    RefPtr<Event> event = MediaKeyEvent::create(eventNames().webkitkeyerrorEvent, initializer);
    event->setTarget(this);
    m_asyncEventQueue.enqueueEvent(event.release());
}

void HTMLMediaElement::mediaPlayerKeyMessage(MediaPlayer*, const String& keySystem, const String& sessionId, const unsigned char* message, unsigned messageLength, const URL& defaultURL)
{
    MediaKeyEventInit initializer;
    initializer.keySystem = keySystem;
    initializer.sessionId = sessionId;
    initializer.message = Uint8Array::create(message, messageLength);
    initializer.defaultURL = defaultURL; 
    initializer.bubbles = false;
    initializer.cancelable = false;

    RefPtr<Event> event = MediaKeyEvent::create(eventNames().webkitkeymessageEvent, initializer);
    event->setTarget(this);
    m_asyncEventQueue.enqueueEvent(event.release());
}

bool HTMLMediaElement::mediaPlayerKeyNeeded(MediaPlayer*, const String& keySystem, const String& sessionId, const unsigned char* initData, unsigned initDataLength)
{
    if (!hasEventListeners(eventNames().webkitneedkeyEvent)) {
        m_error = MediaError::create(MediaError::MEDIA_ERR_ENCRYPTED);
        scheduleEvent(eventNames().errorEvent);
        return false;
    }

    MediaKeyEventInit initializer;
    initializer.keySystem = keySystem;
    initializer.sessionId = sessionId;
    initializer.initData = Uint8Array::create(initData, initDataLength);
    initializer.bubbles = false;
    initializer.cancelable = false;

    RefPtr<Event> event = MediaKeyEvent::create(eventNames().webkitneedkeyEvent, initializer);
    event->setTarget(this);
    m_asyncEventQueue.enqueueEvent(event.release());
    return true;
}
#endif

#if ENABLE(ENCRYPTED_MEDIA_V2)
RefPtr<ArrayBuffer> HTMLMediaElement::mediaPlayerCachedKeyForKeyId(const String& keyId) const
{
    return m_mediaKeys ? m_mediaKeys->cachedKeyForKeyId(keyId) : nullptr;
}

bool HTMLMediaElement::mediaPlayerKeyNeeded(MediaPlayer*, Uint8Array* initData)
{
    if (!hasEventListeners("webkitneedkey")) {
        m_error = MediaError::create(MediaError::MEDIA_ERR_ENCRYPTED);
        scheduleEvent(eventNames().errorEvent);
        return false;
    }

    MediaKeyNeededEventInit initializer;
    initializer.initData = initData;
    initializer.bubbles = false;
    initializer.cancelable = false;

    RefPtr<Event> event = MediaKeyNeededEvent::create(eventNames().webkitneedkeyEvent, initializer);
    event->setTarget(this);
    m_asyncEventQueue.enqueueEvent(event.release());

    return true;
}

String HTMLMediaElement::mediaPlayerMediaKeysStorageDirectory() const
{
    Settings* settings = document().settings();
    if (!settings)
        return emptyString();

    String storageDirectory = settings->mediaKeysStorageDirectory();
    if (storageDirectory.isEmpty())
        return emptyString();

    SecurityOrigin* origin = document().securityOrigin();
    if (!origin)
        return emptyString();

    return pathByAppendingComponent(storageDirectory, origin->databaseIdentifier());
}

void HTMLMediaElement::setMediaKeys(MediaKeys* mediaKeys)
{
    if (m_mediaKeys == mediaKeys)
        return;

    if (m_mediaKeys)
        m_mediaKeys->setMediaElement(0);
    m_mediaKeys = mediaKeys;
    if (m_mediaKeys)
        m_mediaKeys->setMediaElement(this);
}

void HTMLMediaElement::keyAdded()
{
    if (m_player)
        m_player->keyAdded();
}
#endif

void HTMLMediaElement::progressEventTimerFired()
{
    ASSERT(m_player);
    if (m_networkState != NETWORK_LOADING)
        return;

    double time = monotonicallyIncreasingTime();
    double timedelta = time - m_previousProgressTime;

    if (m_player->didLoadingProgress()) {
        scheduleEvent(eventNames().progressEvent);
        m_previousProgressTime = time;
        m_sentStalledEvent = false;
        if (renderer())
            renderer()->updateFromElement();
        if (hasMediaControls())
            mediaControls()->bufferingProgressed();
    } else if (timedelta > 3.0 && !m_sentStalledEvent) {
        scheduleEvent(eventNames().stalledEvent);
        m_sentStalledEvent = true;
        setShouldDelayLoadEvent(false);
    }
}

void HTMLMediaElement::rewind(double timeDelta)
{
    LOG(Media, "HTMLMediaElement::rewind(%p) - %f", this, timeDelta);
    setCurrentTime(std::max(currentMediaTime() - MediaTime::createWithDouble(timeDelta), minTimeSeekable()));
}

void HTMLMediaElement::returnToRealtime()
{
    LOG(Media, "HTMLMediaElement::returnToRealtime(%p)", this);
    setCurrentTime(maxTimeSeekable());
}

void HTMLMediaElement::addPlayedRange(const MediaTime& start, const MediaTime& end)
{
    LOG(Media, "HTMLMediaElement::addPlayedRange(%p) - [%s, %s]", this, toString(start).utf8().data(), toString(end).utf8().data());
    if (!m_playedTimeRanges)
        m_playedTimeRanges = TimeRanges::create();
    m_playedTimeRanges->ranges().add(start, end);
}  

bool HTMLMediaElement::supportsScanning() const
{
    return m_player ? m_player->supportsScanning() : false;
}

void HTMLMediaElement::prepareToPlay()
{
    LOG(Media, "HTMLMediaElement::prepareToPlay(%p)", this);
    if (m_havePreparedToPlay)
        return;
    m_havePreparedToPlay = true;
    m_player->prepareToPlay();
}

void HTMLMediaElement::fastSeek(double time)
{
    fastSeek(MediaTime::createWithDouble(time));
}

void HTMLMediaElement::fastSeek(const MediaTime& time)
{
    LOG(Media, "HTMLMediaElement::fastSeek(%p) - %s", this, toString(time).utf8().data());
    // 4.7.10.9 Seeking
    // 9. If the approximate-for-speed flag is set, adjust the new playback position to a value that will
    // allow for playback to resume promptly. If new playback position before this step is before current
    // playback position, then the adjusted new playback position must also be before the current playback
    // position. Similarly, if the new playback position before this step is after current playback position,
    // then the adjusted new playback position must also be after the current playback position.
    refreshCachedTime();
    MediaTime delta = time - currentMediaTime();
    MediaTime negativeTolerance = delta >= MediaTime::zeroTime() ? delta : MediaTime::positiveInfiniteTime();
    MediaTime positiveTolerance = delta < MediaTime::zeroTime() ? -delta : MediaTime::positiveInfiniteTime();

    seekWithTolerance(time, negativeTolerance, positiveTolerance, true);
}

void HTMLMediaElement::seek(const MediaTime& time)
{
    LOG(Media, "HTMLMediaElement::seek(%p) - %s", this, toString(time).utf8().data());
    seekWithTolerance(time, MediaTime::zeroTime(), MediaTime::zeroTime(), true);
}

void HTMLMediaElement::seekInternal(const MediaTime& time)
{
    LOG(Media, "HTMLMediaElement::seekInternal(%p) - %s", this, toString(time).utf8().data());
    seekWithTolerance(time, MediaTime::zeroTime(), MediaTime::zeroTime(), false);
}

void HTMLMediaElement::seekWithTolerance(const MediaTime& inTime, const MediaTime& negativeTolerance, const MediaTime& positiveTolerance, bool fromDOM)
{
    // 4.8.10.9 Seeking
    MediaTime time = inTime;

    // 1 - Set the media element's show poster flag to false.
    setDisplayMode(Video);

    // 2 - If the media element's readyState is HAVE_NOTHING, abort these steps.
    if (m_readyState == HAVE_NOTHING || !m_player)
        return;

    // If the media engine has been told to postpone loading data, let it go ahead now.
    if (m_preload < MediaPlayer::Auto && m_readyState < HAVE_FUTURE_DATA)
        prepareToPlay();

    // Get the current time before setting m_seeking, m_lastSeekTime is returned once it is set.
    refreshCachedTime();
    MediaTime now = currentMediaTime();

    // 3 - If the element's seeking IDL attribute is true, then another instance of this algorithm is
    // already running. Abort that other instance of the algorithm without waiting for the step that
    // it is running to complete.
    if (m_seekTaskQueue.hasPendingTasks()) {
        m_seekTaskQueue.cancelAllTasks();
        m_pendingSeek = nullptr;
    }

    // 4 - Set the seeking IDL attribute to true.
    // The flag will be cleared when the engine tells us the time has actually changed.
    m_seeking = true;
    if (m_playing) {
        if (m_lastSeekTime < now)
            addPlayedRange(m_lastSeekTime, now);
    }
    m_lastSeekTime = time;

    // 5 - If the seek was in response to a DOM method call or setting of an IDL attribute, then continue
    // the script. The remainder of these steps must be run asynchronously.
    m_pendingSeek = std::make_unique<PendingSeek>(now, time, negativeTolerance, positiveTolerance);
    if (fromDOM)
        m_seekTaskQueue.enqueueTask(std::bind(&HTMLMediaElement::seekTask, this));
    else
        seekTask();
}

void HTMLMediaElement::seekTask()
{
    if (!m_player) {
        m_seeking = false;
        return;
    }

    ASSERT(m_pendingSeek);
    MediaTime now = m_pendingSeek->now;
    MediaTime time = m_pendingSeek->targetTime;
    MediaTime negativeTolerance = m_pendingSeek->negativeTolerance;
    MediaTime positiveTolerance = m_pendingSeek->positiveTolerance;
    m_pendingSeek = nullptr;

    // 6 - If the new playback position is later than the end of the media resource, then let it be the end 
    // of the media resource instead.
    time = std::min(time, durationMediaTime());

    // 7 - If the new playback position is less than the earliest possible position, let it be that position instead.
    MediaTime earliestTime = m_player->startTime();
    time = std::max(time, earliestTime);

    // Ask the media engine for the time value in the movie's time scale before comparing with current time. This
    // is necessary because if the seek time is not equal to currentTime but the delta is less than the movie's
    // time scale, we will ask the media engine to "seek" to the current movie time, which may be a noop and
    // not generate a timechanged callback. This means m_seeking will never be cleared and we will never 
    // fire a 'seeked' event.
#if !LOG_DISABLED
    MediaTime mediaTime = m_player->mediaTimeForTimeValue(time);
    if (time != mediaTime)
        LOG(Media, "HTMLMediaElement::seekTimerFired(%p) - %s - media timeline equivalent is %s", this, toString(time).utf8().data(), toString(mediaTime).utf8().data());
#endif
    time = m_player->mediaTimeForTimeValue(time);

    // 8 - If the (possibly now changed) new playback position is not in one of the ranges given in the
    // seekable attribute, then let it be the position in one of the ranges given in the seekable attribute 
    // that is the nearest to the new playback position. ... If there are no ranges given in the seekable
    // attribute then set the seeking IDL attribute to false and abort these steps.
    RefPtr<TimeRanges> seekableRanges = seekable();

    // Short circuit seeking to the current time by just firing the events if no seek is required.
    // Don't skip calling the media engine if we are in poster mode because a seek should always 
    // cancel poster display.
    bool noSeekRequired = !seekableRanges->length() || (time == now && displayMode() != Poster);

#if ENABLE(MEDIA_SOURCE)
    // Always notify the media engine of a seek if the source is not closed. This ensures that the source is
    // always in a flushed state when the 'seeking' event fires.
    if (m_mediaSource && !m_mediaSource->isClosed())
        noSeekRequired = false;
#endif

    if (noSeekRequired) {
        if (time == now) {
            scheduleEvent(eventNames().seekingEvent);
            scheduleTimeupdateEvent(false);
            scheduleEvent(eventNames().seekedEvent);
        }
        m_seeking = false;
        return;
    }
    time = seekableRanges->ranges().nearest(time);

    m_sentEndEvent = false;
    m_lastSeekTime = time;

    // 10 - Queue a task to fire a simple event named seeking at the element.
    scheduleEvent(eventNames().seekingEvent);

    // 11 - Set the current playback position to the given new playback position
    m_player->seekWithTolerance(time, negativeTolerance, positiveTolerance);

    // 12 - Wait until the user agent has established whether or not the media data for the new playback
    // position is available, and, if it is, until it has decoded enough data to play back that position.
    // 13 - Await a stable state. The synchronous section consists of all the remaining steps of this algorithm.
}

void HTMLMediaElement::finishSeek()
{
    LOG(Media, "HTMLMediaElement::finishSeek(%p)", this);

    // 4.8.10.9 Seeking
    // 14 - Set the seeking IDL attribute to false.
    m_seeking = false;

    // 15 - Run the time maches on steps.
    // Handled by mediaPlayerTimeChanged().

    // 16 - Queue a task to fire a simple event named timeupdate at the element.
    scheduleEvent(eventNames().timeupdateEvent);

    // 17 - Queue a task to fire a simple event named seeked at the element.
    scheduleEvent(eventNames().seekedEvent);

#if ENABLE(MEDIA_SOURCE)
    if (m_mediaSource)
        m_mediaSource->monitorSourceBuffers();
#endif
}

HTMLMediaElement::ReadyState HTMLMediaElement::readyState() const
{
    return m_readyState;
}

MediaPlayer::MovieLoadType HTMLMediaElement::movieLoadType() const
{
    return m_player ? m_player->movieLoadType() : MediaPlayer::Unknown;
}

bool HTMLMediaElement::hasAudio() const
{
    return m_player ? m_player->hasAudio() : false;
}

bool HTMLMediaElement::seeking() const
{
    return m_seeking;
}

void HTMLMediaElement::refreshCachedTime() const
{
    if (!m_player)
        return;

    m_cachedTime = m_player->currentTime();
    if (!m_cachedTime) {
        // Do not use m_cachedTime until the media engine returns a non-zero value because we can't 
        // estimate current time until playback actually begins. 
        invalidateCachedTime(); 
        return; 
    } 

    m_clockTimeAtLastCachedTimeUpdate = monotonicallyIncreasingTime();
}

void HTMLMediaElement::invalidateCachedTime() const
{
    if (!m_player || !m_player->maximumDurationToCacheMediaTime())
        return;

#if !LOG_DISABLED
    if (m_cachedTime.isValid())
        LOG(Media, "HTMLMediaElement::invalidateCachedTime(%p)", this);
#endif

    // Don't try to cache movie time when playback first starts as the time reported by the engine
    // sometimes fluctuates for a short amount of time, so the cached time will be off if we take it
    // too early.
    static const double minimumTimePlayingBeforeCacheSnapshot = 0.5;

    m_minimumClockTimeToUpdateCachedTime = monotonicallyIncreasingTime() + minimumTimePlayingBeforeCacheSnapshot;
    m_cachedTime = MediaTime::invalidTime();
}

// playback state
double HTMLMediaElement::currentTime() const
{
    return currentMediaTime().toDouble();
}

MediaTime HTMLMediaElement::currentMediaTime() const
{
#if LOG_CACHED_TIME_WARNINGS
    static const MediaTime minCachedDeltaForWarning = MediaTime::create(1, 100);
#endif

    if (!m_player)
        return MediaTime::zeroTime();

    if (m_seeking) {
        LOG(Media, "HTMLMediaElement::currentTime(%p) - seeking, returning %s", this, toString(m_lastSeekTime).utf8().data());
        return m_lastSeekTime;
    }

    if (m_cachedTime.isValid() && m_paused) {
#if LOG_CACHED_TIME_WARNINGS
        MediaTime delta = m_cachedTime - m_player->currentTime();
        if (delta > minCachedDeltaForWarning)
            LOG(Media, "HTMLMediaElement::currentTime(%p) - WARNING, cached time is %s seconds off of media time when paused", this, toString(delta).utf8().data());
#endif
        return m_cachedTime;
    }

    // Is it too soon use a cached time?
    double now = monotonicallyIncreasingTime();
    double maximumDurationToCacheMediaTime = m_player->maximumDurationToCacheMediaTime();

    if (maximumDurationToCacheMediaTime && m_cachedTime.isValid() && !m_paused && now > m_minimumClockTimeToUpdateCachedTime) {
        double clockDelta = now - m_clockTimeAtLastCachedTimeUpdate;

        // Not too soon, use the cached time only if it hasn't expired.
        if (clockDelta < maximumDurationToCacheMediaTime) {
            MediaTime adjustedCacheTime = m_cachedTime + MediaTime::createWithDouble(effectivePlaybackRate() * clockDelta);

#if LOG_CACHED_TIME_WARNINGS
            MediaTime delta = adjustedCacheTime - m_player->currentTime();
            if (delta > minCachedDeltaForWarning)
                LOG(Media, "HTMLMediaElement::currentTime(%p) - WARNING, cached time is %f seconds off of media time when playing", this, delta);
#endif
            return adjustedCacheTime;
        }
    }

#if LOG_CACHED_TIME_WARNINGS
    if (maximumDurationToCacheMediaTime && now > m_minimumClockTimeToUpdateCachedTime && m_cachedTime != MediaPlayer::invalidTime()) {
        double clockDelta = now - m_clockTimeAtLastCachedTimeUpdate;
        MediaTime delta = m_cachedTime + MediaTime::createWithDouble(effectivePlaybackRate() * clockDelta) - m_player->currentTime();
        LOG(Media, "HTMLMediaElement::currentTime(%p) - cached time was %s seconds off of media time when it expired", this, toString(delta).utf8().data());
    }
#endif

    refreshCachedTime();

    if (m_cachedTime.isInvalid())
        return MediaTime::zeroTime();
    
    return m_cachedTime;
}

void HTMLMediaElement::setCurrentTime(double time)
{
    setCurrentTime(MediaTime::createWithDouble(time));
}

void HTMLMediaElement::setCurrentTime(const MediaTime& time)
{
    if (m_mediaController)
        return;

    seekInternal(time);
}

void HTMLMediaElement::setCurrentTime(double time, ExceptionCode& ec)
{
    // On setting, if the media element has a current media controller, then the user agent must
    // throw an InvalidStateError exception
    if (m_mediaController) {
        ec = INVALID_STATE_ERR;
        return;
    }

    seek(MediaTime::createWithDouble(time));
}

double HTMLMediaElement::duration() const
{
    return durationMediaTime().toDouble();
}

MediaTime HTMLMediaElement::durationMediaTime() const
{
    if (m_player && m_readyState >= HAVE_METADATA)
        return m_player->duration();

    return MediaTime::invalidTime();
}

bool HTMLMediaElement::paused() const
{
    // As of this writing, JavaScript garbage collection calls this function directly. In the past
    // we had problems where this was called on an object after a bad cast. The assertion below
    // made our regression test detect the problem, so we should keep it because of that. But note
    // that the value of the assertion relies on the compiler not being smart enough to know that
    // isHTMLUnknownElement is guaranteed to return false for an HTMLMediaElement.
    ASSERT(!isHTMLUnknownElement());

    return m_paused;
}

double HTMLMediaElement::defaultPlaybackRate() const
{
    return m_defaultPlaybackRate;
}

void HTMLMediaElement::setDefaultPlaybackRate(double rate)
{
    if (m_defaultPlaybackRate != rate) {
        LOG(Media, "HTMLMediaElement::setDefaultPlaybackRate(%p) - %f", this, rate);
        m_defaultPlaybackRate = rate;
        scheduleEvent(eventNames().ratechangeEvent);
    }
}

double HTMLMediaElement::effectivePlaybackRate() const
{
    return m_mediaController ? m_mediaController->playbackRate() : m_reportedPlaybackRate;
}

double HTMLMediaElement::requestedPlaybackRate() const
{
    return m_mediaController ? m_mediaController->playbackRate() : m_requestedPlaybackRate;
}

double HTMLMediaElement::playbackRate() const
{
    return m_requestedPlaybackRate;
}

void HTMLMediaElement::setPlaybackRate(double rate)
{
    LOG(Media, "HTMLMediaElement::setPlaybackRate(%p) - %f", this, rate);

    if (m_player && potentiallyPlaying() && m_player->rate() != rate && !m_mediaController)
        m_player->setRate(rate);

    if (m_requestedPlaybackRate != rate) {
        m_reportedPlaybackRate = m_requestedPlaybackRate = rate;
        invalidateCachedTime();
        scheduleEvent(eventNames().ratechangeEvent);
    }
}

void HTMLMediaElement::updatePlaybackRate()
{
    double requestedRate = requestedPlaybackRate();
    if (m_player && potentiallyPlaying() && m_player->rate() != requestedRate)
        m_player->setRate(requestedRate);
}

bool HTMLMediaElement::webkitPreservesPitch() const
{
    return m_webkitPreservesPitch;
}

void HTMLMediaElement::setWebkitPreservesPitch(bool preservesPitch)
{
    LOG(Media, "HTMLMediaElement::setWebkitPreservesPitch(%p) - %s", this, boolString(preservesPitch));

    m_webkitPreservesPitch = preservesPitch;
    
    if (!m_player)
        return;

    m_player->setPreservesPitch(preservesPitch);
}

bool HTMLMediaElement::ended() const
{
    // 4.8.10.8 Playing the media resource
    // The ended attribute must return true if the media element has ended 
    // playback and the direction of playback is forwards, and false otherwise.
    return endedPlayback() && requestedPlaybackRate() > 0;
}

bool HTMLMediaElement::autoplay() const
{
    return fastHasAttribute(autoplayAttr);
}

String HTMLMediaElement::preload() const
{
    switch (m_preload) {
    case MediaPlayer::None:
        return ASCIILiteral("none");
    case MediaPlayer::MetaData:
        return ASCIILiteral("metadata");
    case MediaPlayer::Auto:
        return ASCIILiteral("auto");
    }

    ASSERT_NOT_REACHED();
    return String();
}

void HTMLMediaElement::setPreload(const String& preload)
{
    LOG(Media, "HTMLMediaElement::setPreload(%p) - %s", this, preload.utf8().data());
    setAttribute(preloadAttr, preload);
}

void HTMLMediaElement::play()
{
    LOG(Media, "HTMLMediaElement::play(%p)", this);

    if (!m_mediaSession->playbackPermitted(*this))
        return;
    if (ScriptController::processingUserGesture())
        removeBehaviorsRestrictionsAfterFirstUserGesture();

    playInternal();
}

void HTMLMediaElement::playInternal()
{
    LOG(Media, "HTMLMediaElement::playInternal(%p)", this);
    
    if (!m_mediaSession->clientWillBeginPlayback()) {
        LOG(Media, "  returning because of interruption");
        return;
    }
    
    // 4.8.10.9. Playing the media resource
    if (!m_player || m_networkState == NETWORK_EMPTY)
        scheduleDelayedAction(LoadMediaResource);

    if (endedPlayback())
        seekInternal(MediaTime::zeroTime());

    if (m_mediaController)
        m_mediaController->bringElementUpToSpeed(this);

    if (m_paused) {
        m_paused = false;
        invalidateCachedTime();
        scheduleEvent(eventNames().playEvent);

        if (m_readyState <= HAVE_CURRENT_DATA)
            scheduleEvent(eventNames().waitingEvent);
        else if (m_readyState >= HAVE_FUTURE_DATA)
            scheduleEvent(eventNames().playingEvent);

#if ENABLE(MEDIA_SESSION)
        // 6.3 Activating a media session from a media element
        // When the play() method is invoked, the paused attribute is true, and the readyState attribute has the value
        // HAVE_FUTURE_DATA or HAVE_ENOUGH_DATA, then
        // 1. Let media session be the value of the current media session.
        // 2. If we are not currently in media session's list of active participating media elements then append
        //    ourselves to this list.
        if (m_readyState == HAVE_ENOUGH_DATA || m_readyState == HAVE_FUTURE_DATA) {
            if (m_session)
                m_session->addActiveMediaElement(*this);
        }
#endif
    }
    m_autoplaying = false;
    updatePlayState();
    updateMediaController();
}

void HTMLMediaElement::pause()
{
    LOG(Media, "HTMLMediaElement::pause(%p)", this);

    if (!m_mediaSession->playbackPermitted(*this))
        return;

    pauseInternal();
}


void HTMLMediaElement::pauseInternal()
{
    LOG(Media, "HTMLMediaElement::pauseInternal(%p)", this);

    if (!m_mediaSession->clientWillPausePlayback()) {
        LOG(Media, "  returning because of interruption");
        return;
    }
    
    // 4.8.10.9. Playing the media resource
    if (!m_player || m_networkState == NETWORK_EMPTY) {
        // Unless the restriction on media requiring user action has been lifted
        // don't trigger loading if a script calls pause().
        if (!m_mediaSession->playbackPermitted(*this))
            return;
        scheduleDelayedAction(LoadMediaResource);
    }

    m_autoplaying = false;

    if (!m_paused) {
        m_paused = true;
        scheduleTimeupdateEvent(false);
        scheduleEvent(eventNames().pauseEvent);
    }

    updatePlayState();
}

#if ENABLE(MEDIA_SOURCE)
void HTMLMediaElement::closeMediaSource()
{
    if (!m_mediaSource)
        return;

    m_mediaSource->close();
    m_mediaSource = 0;
}
#endif

#if ENABLE(ENCRYPTED_MEDIA)
void HTMLMediaElement::webkitGenerateKeyRequest(const String& keySystem, PassRefPtr<Uint8Array> initData, ExceptionCode& ec)
{
#if ENABLE(ENCRYPTED_MEDIA_V2)
    static bool firstTime = true;
    if (firstTime && scriptExecutionContext()) {
        scriptExecutionContext()->addConsoleMessage(MessageSource::JS, MessageLevel::Warning, ASCIILiteral("'HTMLMediaElement.webkitGenerateKeyRequest()' is deprecated.  Use 'MediaKeys.createSession()' instead."));
        firstTime = false;
    }
#endif

    if (keySystem.isEmpty()) {
        ec = SYNTAX_ERR;
        return;
    }

    if (!m_player) {
        ec = INVALID_STATE_ERR;
        return;
    }

    const unsigned char* initDataPointer = 0;
    unsigned initDataLength = 0;
    if (initData) {
        initDataPointer = initData->data();
        initDataLength = initData->length();
    }

    MediaPlayer::MediaKeyException result = m_player->generateKeyRequest(keySystem, initDataPointer, initDataLength);
    ec = exceptionCodeForMediaKeyException(result);
}

void HTMLMediaElement::webkitGenerateKeyRequest(const String& keySystem, ExceptionCode& ec)
{
    webkitGenerateKeyRequest(keySystem, Uint8Array::create(0), ec);
}

void HTMLMediaElement::webkitAddKey(const String& keySystem, PassRefPtr<Uint8Array> key, PassRefPtr<Uint8Array> initData, const String& sessionId, ExceptionCode& ec)
{
#if ENABLE(ENCRYPTED_MEDIA_V2)
    static bool firstTime = true;
    if (firstTime && scriptExecutionContext()) {
        scriptExecutionContext()->addConsoleMessage(MessageSource::JS, MessageLevel::Warning, ASCIILiteral("'HTMLMediaElement.webkitAddKey()' is deprecated.  Use 'MediaKeySession.update()' instead."));
        firstTime = false;
    }
#endif

    if (keySystem.isEmpty()) {
        ec = SYNTAX_ERR;
        return;
    }

    if (!key) {
        ec = SYNTAX_ERR;
        return;
    }

    if (!key->length()) {
        ec = TYPE_MISMATCH_ERR;
        return;
    }

    if (!m_player) {
        ec = INVALID_STATE_ERR;
        return;
    }

    const unsigned char* initDataPointer = 0;
    unsigned initDataLength = 0;
    if (initData) {
        initDataPointer = initData->data();
        initDataLength = initData->length();
    }

    MediaPlayer::MediaKeyException result = m_player->addKey(keySystem, key->data(), key->length(), initDataPointer, initDataLength, sessionId);
    ec = exceptionCodeForMediaKeyException(result);
}

void HTMLMediaElement::webkitAddKey(const String& keySystem, PassRefPtr<Uint8Array> key, ExceptionCode& ec)
{
    webkitAddKey(keySystem, key, Uint8Array::create(0), String(), ec);
}

void HTMLMediaElement::webkitCancelKeyRequest(const String& keySystem, const String& sessionId, ExceptionCode& ec)
{
    if (keySystem.isEmpty()) {
        ec = SYNTAX_ERR;
        return;
    }

    if (!m_player) {
        ec = INVALID_STATE_ERR;
        return;
    }

    MediaPlayer::MediaKeyException result = m_player->cancelKeyRequest(keySystem, sessionId);
    ec = exceptionCodeForMediaKeyException(result);
}

#endif

bool HTMLMediaElement::loop() const
{
    return fastHasAttribute(loopAttr);
}

void HTMLMediaElement::setLoop(bool b)
{
    LOG(Media, "HTMLMediaElement::setLoop(%p) - %s", this, boolString(b));
    setBooleanAttribute(loopAttr, b);
}

bool HTMLMediaElement::controls() const
{
    Frame* frame = document().frame();

    // always show controls when scripting is disabled
    if (frame && !frame->script().canExecuteScripts(NotAboutToExecuteScript))
        return true;

    return fastHasAttribute(controlsAttr);
}

void HTMLMediaElement::setControls(bool b)
{
    LOG(Media, "HTMLMediaElement::setControls(%p) - %s", this, boolString(b));
    setBooleanAttribute(controlsAttr, b);
}

double HTMLMediaElement::volume() const
{
    return m_volume;
}

void HTMLMediaElement::setVolume(double vol, ExceptionCode& ec)
{
    LOG(Media, "HTMLMediaElement::setVolume(%p) - %f", this, vol);

    if (vol < 0.0f || vol > 1.0f) {
        ec = INDEX_SIZE_ERR;
        return;
    }
    
#if !PLATFORM(IOS)
    if (m_volume != vol) {
        m_volume = vol;
        m_volumeInitialized = true;
        updateVolume();
        scheduleEvent(eventNames().volumechangeEvent);
    }
#endif
}

bool HTMLMediaElement::muted() const
{
    return m_explicitlyMuted ? m_muted : fastHasAttribute(mutedAttr);
}

void HTMLMediaElement::setMuted(bool muted)
{
    LOG(Media, "HTMLMediaElement::setMuted(%p) - %s", this, boolString(muted));

#if PLATFORM(IOS)
    UNUSED_PARAM(muted);
#else
    if (m_muted != muted || !m_explicitlyMuted) {
        m_muted = muted;
        m_explicitlyMuted = true;
        // Avoid recursion when the player reports volume changes.
        if (!processingMediaPlayerCallback()) {
            if (m_player) {
                m_player->setMuted(effectiveMuted());
                if (hasMediaControls())
                    mediaControls()->changedMute();
            }
        }
        scheduleEvent(eventNames().volumechangeEvent);
        document().updateIsPlayingMedia();

#if ENABLE(WIRELESS_PLAYBACK_TARGET)
        updateMediaState();
#endif
    }
#endif
}

void HTMLMediaElement::togglePlayState()
{
    LOG(Media, "HTMLMediaElement::togglePlayState(%p) - canPlay() is %s", this, boolString(canPlay()));

    // We can safely call the internal play/pause methods, which don't check restrictions, because
    // this method is only called from the built-in media controller
    if (canPlay()) {
        updatePlaybackRate();
        playInternal();
    } else 
        pauseInternal();
}

void HTMLMediaElement::beginScrubbing()
{
    LOG(Media, "HTMLMediaElement::beginScrubbing(%p) - paused() is %s", this, boolString(paused()));

    if (!paused()) {
        if (ended()) {
            // Because a media element stays in non-paused state when it reaches end, playback resumes 
            // when the slider is dragged from the end to another position unless we pause first. Do 
            // a "hard pause" so an event is generated, since we want to stay paused after scrubbing finishes.
            pause();
        } else {
            // Not at the end but we still want to pause playback so the media engine doesn't try to
            // continue playing during scrubbing. Pause without generating an event as we will 
            // unpause after scrubbing finishes.
            setPausedInternal(true);
        }
    }
}

void HTMLMediaElement::endScrubbing()
{
    LOG(Media, "HTMLMediaElement::endScrubbing(%p) - m_pausedInternal is %s", this, boolString(m_pausedInternal));

    if (m_pausedInternal)
        setPausedInternal(false);
}

void HTMLMediaElement::beginScanning(ScanDirection direction)
{
    m_scanType = supportsScanning() ? Scan : Seek;
    m_scanDirection = direction;

    if (m_scanType == Seek) {
        // Scanning by seeking requires the video to be paused during scanning.
        m_actionAfterScan = paused() ? Nothing : Play;
        pause();
    } else {
        // Scanning by scanning requires the video to be playing during scanninging.
        m_actionAfterScan = paused() ? Pause : Nothing;
        play();
        setPlaybackRate(nextScanRate());
    }

    m_scanTimer.start(0, m_scanType == Seek ? SeekRepeatDelay : ScanRepeatDelay);
}

void HTMLMediaElement::endScanning()
{
    if (m_scanType == Scan)
        setPlaybackRate(defaultPlaybackRate());

    if (m_actionAfterScan == Play)
        play();
    else if (m_actionAfterScan == Pause)
        pause();

    if (m_scanTimer.isActive())
        m_scanTimer.stop();
}

double HTMLMediaElement::nextScanRate()
{
    double rate = std::min(ScanMaximumRate, fabs(playbackRate() * 2));
    if (m_scanDirection == Backward)
        rate *= -1;
#if PLATFORM(IOS)
    rate = std::min(std::max(rate, minFastReverseRate()), maxFastForwardRate());
#endif
    return rate;
}

void HTMLMediaElement::scanTimerFired()
{
    if (m_scanType == Seek) {
        double seekTime = m_scanDirection == Forward ? SeekTime : -SeekTime;
        setCurrentTime(currentTime() + seekTime);
    } else
        setPlaybackRate(nextScanRate());
}

// The spec says to fire periodic timeupdate events (those sent while playing) every
// "15 to 250ms", we choose the slowest frequency
static const double maxTimeupdateEventFrequency = 0.25;

void HTMLMediaElement::startPlaybackProgressTimer()
{
    if (m_playbackProgressTimer.isActive())
        return;

    m_previousProgressTime = monotonicallyIncreasingTime();
    m_playbackProgressTimer.startRepeating(maxTimeupdateEventFrequency);
}

void HTMLMediaElement::playbackProgressTimerFired()
{
    ASSERT(m_player);

    if (m_fragmentEndTime.isValid() && currentMediaTime() >= m_fragmentEndTime && requestedPlaybackRate() > 0) {
        m_fragmentEndTime = MediaTime::invalidTime();
        if (!m_mediaController && !m_paused) {
            // changes paused to true and fires a simple event named pause at the media element.
            pauseInternal();
        }
    }
    
    scheduleTimeupdateEvent(true);

    if (!requestedPlaybackRate())
        return;

    if (!m_paused && hasMediaControls())
        mediaControls()->playbackProgressed();

#if ENABLE(VIDEO_TRACK)
    if (RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        updateActiveTextTrackCues(currentMediaTime());
#endif

#if ENABLE(MEDIA_SOURCE)
    if (m_mediaSource)
        m_mediaSource->monitorSourceBuffers();
#endif
}

void HTMLMediaElement::scheduleTimeupdateEvent(bool periodicEvent)
{
    double now = monotonicallyIncreasingTime();
    double timedelta = now - m_clockTimeAtLastUpdateEvent;

    // throttle the periodic events
    if (periodicEvent && timedelta < maxTimeupdateEventFrequency)
        return;

    // Some media engines make multiple "time changed" callbacks at the same time, but we only want one
    // event at a given time so filter here
    MediaTime movieTime = currentMediaTime();
    if (movieTime != m_lastTimeUpdateEventMovieTime) {
        scheduleEvent(eventNames().timeupdateEvent);
        m_clockTimeAtLastUpdateEvent = now;
        m_lastTimeUpdateEventMovieTime = movieTime;
    }
}

bool HTMLMediaElement::canPlay() const
{
    return paused() || ended() || m_readyState < HAVE_METADATA;
}

double HTMLMediaElement::percentLoaded() const
{
    if (!m_player)
        return 0;
    MediaTime duration = m_player->duration();

    if (!duration || duration.isPositiveInfinite() || duration.isNegativeInfinite())
        return 0;

    MediaTime buffered = MediaTime::zeroTime();
    bool ignored;
    std::unique_ptr<PlatformTimeRanges> timeRanges = m_player->buffered();
    for (unsigned i = 0; i < timeRanges->length(); ++i) {
        MediaTime start = timeRanges->start(i, ignored);
        MediaTime end = timeRanges->end(i, ignored);
        buffered += end - start;
    }
    return buffered.toDouble() / duration.toDouble();
}

#if ENABLE(VIDEO_TRACK)

void HTMLMediaElement::mediaPlayerDidAddAudioTrack(PassRefPtr<AudioTrackPrivate> prpTrack)
{
    if (isPlaying() && !m_mediaSession->playbackPermitted(*this))
        pauseInternal();

    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    addAudioTrack(AudioTrack::create(this, prpTrack));
}

void HTMLMediaElement::mediaPlayerDidAddTextTrack(PassRefPtr<InbandTextTrackPrivate> prpTrack)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;
    
    // 4.8.10.12.2 Sourcing in-band text tracks
    // 1. Associate the relevant data with a new text track and its corresponding new TextTrack object.
    RefPtr<InbandTextTrack> textTrack = InbandTextTrack::create(ActiveDOMObject::scriptExecutionContext(), this, prpTrack);
    textTrack->setMediaElement(this);
    
    // 2. Set the new text track's kind, label, and language based on the semantics of the relevant data,
    // as defined by the relevant specification. If there is no label in that data, then the label must
    // be set to the empty string.
    // 3. Associate the text track list of cues with the rules for updating the text track rendering appropriate
    // for the format in question.
    // 4. If the new text track's kind is metadata, then set the text track in-band metadata track dispatch type
    // as follows, based on the type of the media resource:
    // 5. Populate the new text track's list of cues with the cues parsed so far, folllowing the guidelines for exposing
    // cues, and begin updating it dynamically as necessary.
    //   - Thess are all done by the media engine.
    
    // 6. Set the new text track's readiness state to loaded.
    textTrack->setReadinessState(TextTrack::Loaded);
    
    // 7. Set the new text track's mode to the mode consistent with the user's preferences and the requirements of
    // the relevant specification for the data.
    //  - This will happen in configureTextTracks()
    scheduleDelayedAction(ConfigureTextTracks);
    
    // 8. Add the new text track to the media element's list of text tracks.
    // 9. Fire an event with the name addtrack, that does not bubble and is not cancelable, and that uses the TrackEvent
    // interface, with the track attribute initialized to the text track's TextTrack object, at the media element's
    // textTracks attribute's TextTrackList object.
    addTextTrack(textTrack.release());
}

void HTMLMediaElement::mediaPlayerDidAddVideoTrack(PassRefPtr<VideoTrackPrivate> prpTrack)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    addVideoTrack(VideoTrack::create(this, prpTrack));
}

void HTMLMediaElement::mediaPlayerDidRemoveAudioTrack(PassRefPtr<AudioTrackPrivate> prpTrack)
{
    prpTrack->willBeRemoved();
}

void HTMLMediaElement::mediaPlayerDidRemoveTextTrack(PassRefPtr<InbandTextTrackPrivate> prpTrack)
{
    prpTrack->willBeRemoved();
}

void HTMLMediaElement::mediaPlayerDidRemoveVideoTrack(PassRefPtr<VideoTrackPrivate> prpTrack)
{
    prpTrack->willBeRemoved();
}

#if USE(PLATFORM_TEXT_TRACK_MENU)
void HTMLMediaElement::setSelectedTextTrack(PassRefPtr<PlatformTextTrack> platformTrack)
{
    if (!m_textTracks)
        return;

    TrackDisplayUpdateScope scope(this);

    if (!platformTrack) {
        setSelectedTextTrack(TextTrack::captionMenuOffItem());
        return;
    }

    TextTrack* textTrack;
    if (platformTrack == PlatformTextTrack::captionMenuOffItem())
        textTrack = TextTrack::captionMenuOffItem();
    else if (platformTrack == PlatformTextTrack::captionMenuAutomaticItem())
        textTrack = TextTrack::captionMenuAutomaticItem();
    else {
        size_t i;
        for (i = 0; i < m_textTracks->length(); ++i) {
            textTrack = m_textTracks->item(i);
            
            if (textTrack->platformTextTrack() == platformTrack)
                break;
        }
        if (i == m_textTracks->length())
            return;
    }

    setSelectedTextTrack(textTrack);
}

Vector<RefPtr<PlatformTextTrack>> HTMLMediaElement::platformTextTracks()
{
    if (!m_textTracks || !m_textTracks->length())
        return Vector<RefPtr<PlatformTextTrack>>();
    
    Vector<RefPtr<PlatformTextTrack>> platformTracks;
    for (size_t i = 0; i < m_textTracks->length(); ++i)
        platformTracks.append(m_textTracks->item(i)->platformTextTrack());
    
    return platformTracks;
}

void HTMLMediaElement::notifyMediaPlayerOfTextTrackChanges()
{
    if (!m_textTracks || !m_textTracks->length() || !platformTextTrackMenu())
        return;
    
    m_platformMenu->tracksDidChange();
}

PlatformTextTrackMenuInterface* HTMLMediaElement::platformTextTrackMenu()
{
    if (m_platformMenu)
        return m_platformMenu.get();

    if (!m_player || !m_player->implementsTextTrackControls())
        return 0;

    m_platformMenu = m_player->textTrackMenu();
    if (!m_platformMenu)
        return 0;

    m_platformMenu->setClient(this);

    return m_platformMenu.get();
}
#endif // #if USE(PLATFORM_TEXT_TRACK_MENU)
    
void HTMLMediaElement::closeCaptionTracksChanged()
{
    if (hasMediaControls())
        mediaControls()->closedCaptionTracksChanged();

#if USE(PLATFORM_TEXT_TRACK_MENU)
    if (m_player && m_player->implementsTextTrackControls())
        scheduleDelayedAction(TextTrackChangesNotification);
#endif
}

void HTMLMediaElement::addAudioTrack(PassRefPtr<AudioTrack> track)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    audioTracks()->append(track);
}

void HTMLMediaElement::addTextTrack(PassRefPtr<TextTrack> track)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    if (!m_requireCaptionPreferencesChangedCallbacks) {
        m_requireCaptionPreferencesChangedCallbacks = true;
        document().registerForCaptionPreferencesChangedCallbacks(this);
    }

    textTracks()->append(track);

    closeCaptionTracksChanged();
}

void HTMLMediaElement::addVideoTrack(PassRefPtr<VideoTrack> track)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    videoTracks()->append(track);
}

void HTMLMediaElement::removeAudioTrack(AudioTrack* track)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    m_audioTracks->remove(track);
}

void HTMLMediaElement::removeTextTrack(TextTrack* track, bool scheduleEvent)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    TrackDisplayUpdateScope scope(this);
    TextTrackCueList* cues = track->cues();
    if (cues)
        textTrackRemoveCues(track, cues);
    track->clearClient();
    m_textTracks->remove(track, scheduleEvent);

    closeCaptionTracksChanged();
}

void HTMLMediaElement::removeVideoTrack(VideoTrack* track)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return;

    m_videoTracks->remove(track);
}

void HTMLMediaElement::forgetResourceSpecificTracks()
{
    while (m_audioTracks &&  m_audioTracks->length())
        removeAudioTrack(m_audioTracks->lastItem());

    if (m_textTracks) {
        TrackDisplayUpdateScope scope(this);
        for (int i = m_textTracks->length() - 1; i >= 0; --i) {
            TextTrack* track = m_textTracks->item(i);

            if (track->trackType() == TextTrack::InBand)
                removeTextTrack(track, false);
        }
    }

    while (m_videoTracks &&  m_videoTracks->length())
        removeVideoTrack(m_videoTracks->lastItem());
}

PassRefPtr<TextTrack> HTMLMediaElement::addTextTrack(const String& kind, const String& label, const String& language, ExceptionCode& ec)
{
    if (!RuntimeEnabledFeatures::sharedFeatures().webkitVideoTrackEnabled())
        return 0;

    // 4.8.10.12.4 Text track API
    // The addTextTrack(kind, label, language) method of media elements, when invoked, must run the following steps:

    // 1. If kind is not one of the following strings, then throw a SyntaxError exception and abort these steps
    if (!TextTrack::isValidKindKeyword(kind)) {
        ec = SYNTAX_ERR;
        return 0;
    }

    // 2. If the label argument was omitted, let label be the empty string.