[iOS] When simultaneously exiting-and-entering fullscreen, WebVideoFullscreenManager...

[iOS] When simultaneously exiting-and-entering fullscreen, WebVideoFullscreenManager/Proxy becomes confused about what video element it represents.
https://bugs.webkit.org/show_bug.cgi?id=143680

Reviewed by Simon Fraser.

Source/WebCore:

Add getters for the video's fullscreen layer, and be more tolerant about the order in which setVideoElement() and
setWebVideoFullscreenInterface are called.

* html/HTMLMediaElement.h:
(WebCore::HTMLMediaElement::videoFullscreenLayer): Added simple getter.
* platform/ios/WebVideoFullscreenInterfaceAVKit.h:
* platform/ios/WebVideoFullscreenModelVideoElement.h:
(WebCore::WebVideoFullscreenModelVideoElement::videoElement): Added simple getter.
(WebCore::WebVideoFullscreenModelVideoElement::setWebVideoFullscreenInterface): Deleted. Moved to .mm file.
* platform/ios/WebVideoFullscreenModelVideoElement.mm:
(WebVideoFullscreenModelVideoElement::WebVideoFullscreenModelVideoElement): Initialize ivars in the .h file.
(WebVideoFullscreenModelVideoElement::setWebVideoFullscreenInterface): Call those methods skipped in setVideoElement()
    if m_videoFullscreenInterface had not yet been set.
(WebVideoFullscreenModelVideoElement::setVideoElement): Null-check m_videoFullscreenInterface.

Source/WebKit2:

The original assumption of WebVideoFullscreenManager and -Proxy was that the two classes would represent a
single video element and its full screen state. With multiple animations in and out of fullscreen combined with
multiple fullscreen modes, this assumption no longer holds true.

Rather than having a WebVideoFullscreenManager which /isa/ WebVideoFullscreenModelVideoElement, the manager now
/hasa/ WebVideoFullscreenModelVideoElement (or has many such models). Ditto for WebVideoFullscreenManager and
WebVideoFullscreenInterfaceAVKit. The WebVideoFullscreenInterfaceAVKit still needs a WebVideoFullscreenModel to
communicate with, so a new wrapper class is used for that purpose, WebVideoFullscreenModelContext. Ditto for
WebVideoFullscreenModelVideoElement and the new class WebVideoFullscreenInterfaceContext. These context classes
are paired and share a contextId, allowing the manager and its proxy to route messages between the UIProcess's
WebVideoFullscreenInterfaceAVKit to-and-from the WebProcess's WebVideoFullscreenModelVideoElement.

Both the WebVideoFullscreenModelContext and the WebVideoFullscreenInterfaceContext take a back-pointer to their
manager or manager proxy, and each method on the context simply calls the matching method on the manager and
passes its contextId as a parameter.

Both the WebVideoFullscreenManager and the WebVideoFullscreenManagerProxy pass that contextId in each of their
cross-process messages.

On the other side, the manager and proxy also have a map between contextIds and their matching
WebVideoFullscreenModelVideoElement (in the case of WebVideoFullscreenManager) or
WebVideoFullscreenInterfaceAVKit (in the case of WebVideoFullscreenManagerProxy).

While this change is large by LoC, it is almost entirely boilerplate.  The new and interesting pieces are these:

* UIProcess/ios/WebVideoFullscreenManagerProxy.mm:
(WebKit::WebVideoFullscreenManagerProxy::WebVideoFullscreenManagerProxy): No longer a WebVideoFullscreenInterfaceAVKit.
(WebKit::WebVideoFullscreenManagerProxy::invalidate): Walk through the models and interfaces, invalidating each.
(WebKit::WebVideoFullscreenManagerProxy::createModelAndInterface): Added. Return a new model and interface tuple.
(WebKit::WebVideoFullscreenManagerProxy::ensureModelAndInterface): Added. Lazily create, and add to the m_contextMap
    a new model and interface object.
(WebKit::WebVideoFullscreenManagerProxy::ensureModel): Return the model half of ensureModelAndInterface().
(WebKit::WebVideoFullscreenManagerProxy::ensureInterface): Return the interface half of ensureModelAndInterface().
(WebKit::WebVideoFullscreenManagerProxy::enterFullscreen): Walk through the outstanding interface objects, and if
    any have a fullscreen mode which matches the about-to-be-fullscreen interface, request that that other interface
    exit fullscreen.
* WebProcess/ios/WebVideoFullscreenManager.mm:
(WebKit::nextContextId): Static, incrementing counter used as a contextId source.
(WebKit::WebVideoFullscreenManager::WebVideoFullscreenManager): No longer a WebVideoFullscreenModelVideoElement.
(WebKit::WebVideoFullscreenManager::~WebVideoFullscreenManager): Walk through the models and interfaces, invalidating each.
(WebKit::WebVideoFullscreenManager::ensureModelAndInterface): Added. Return a new model and interface tuple.
(WebKit::WebVideoFullscreenManager::ensureModelAndInterface):  Added. Lazily create, and add to the m_contextMap
    a new model and interface object.
(WebKit::WebVideoFullscreenManager::ensureModel): Return the model half of ensureModelAndInterface().
(WebKit::WebVideoFullscreenManager::ensureInterface): Return the interface half of ensureModelAndInterface().

New classes and methods which just forward on to their owning objects:

* UIProcess/ios/WebVideoFullscreenManagerProxy.h:
(WebKit::WebVideoFullscreenModelContext::create):
(WebKit::WebVideoFullscreenModelContext::~WebVideoFullscreenModelContext):
(WebKit::WebVideoFullscreenModelContext::invalidate):
(WebKit::WebVideoFullscreenModelContext::layerHost):
(WebKit::WebVideoFullscreenModelContext::setLayerHost):
(WebKit::WebVideoFullscreenModelContext::setInitialVideoLayerFrame):
(WebKit::WebVideoFullscreenModelContext::WebVideoFullscreenModelContext):
* UIProcess/ios/WebVideoFullscreenManagerProxy.mm:
(WebKit::WebVideoFullscreenModelContext::play):
(WebKit::WebVideoFullscreenModelContext::pause):
(WebKit::WebVideoFullscreenModelContext::togglePlayState):
(WebKit::WebVideoFullscreenModelContext::beginScrubbing):
(WebKit::WebVideoFullscreenModelContext::endScrubbing):
(WebKit::WebVideoFullscreenModelContext::seekToTime):
(WebKit::WebVideoFullscreenModelContext::fastSeek):
(WebKit::WebVideoFullscreenModelContext::beginScanningForward):
(WebKit::WebVideoFullscreenModelContext::beginScanningBackward):
(WebKit::WebVideoFullscreenModelContext::endScanning):
(WebKit::WebVideoFullscreenModelContext::requestExitFullscreen):
(WebKit::WebVideoFullscreenModelContext::setVideoLayerFrame):
(WebKit::WebVideoFullscreenModelContext::videoLayerFrame):
(WebKit::WebVideoFullscreenModelContext::setVideoLayerGravity):
(WebKit::WebVideoFullscreenModelContext::videoLayerGravity):
(WebKit::WebVideoFullscreenModelContext::selectAudioMediaOption):
(WebKit::WebVideoFullscreenModelContext::selectLegibleMediaOption):
(WebKit::WebVideoFullscreenModelContext::fullscreenModeChanged):
(WebKit::WebVideoFullscreenModelContext::didSetupFullscreen):
(WebKit::WebVideoFullscreenModelContext::didEnterFullscreen):
(WebKit::WebVideoFullscreenModelContext::didExitFullscreen):
(WebKit::WebVideoFullscreenModelContext::didCleanupFullscreen):
(WebKit::WebVideoFullscreenModelContext::fullscreenMayReturnToInline):
* WebProcess/ios/WebVideoFullscreenManager.h:
(WebKit::WebVideoFullscreenInterfaceContext::create):
(WebKit::WebVideoFullscreenInterfaceContext::invalidate):
(WebKit::WebVideoFullscreenInterfaceContext::layerHostingContext):
(WebKit::WebVideoFullscreenInterfaceContext::isAnimating):
(WebKit::WebVideoFullscreenInterfaceContext::setIsAnimating):
(WebKit::WebVideoFullscreenInterfaceContext::targetIsFullscreen):
(WebKit::WebVideoFullscreenInterfaceContext::setTargetIsFullscreen):
(WebKit::WebVideoFullscreenInterfaceContext::fullscreenMode):
(WebKit::WebVideoFullscreenInterfaceContext::setFullscreenMode):
(WebKit::WebVideoFullscreenInterfaceContext::isFullscreen):
(WebKit::WebVideoFullscreenInterfaceContext::setIsFullscreen):
* WebProcess/ios/WebVideoFullscreenManager.mm:
(WebKit::WebVideoFullscreenInterfaceContext::WebVideoFullscreenInterfaceContext):
(WebKit::WebVideoFullscreenInterfaceContext::~WebVideoFullscreenInterfaceContext):
(WebKit::WebVideoFullscreenInterfaceContext::setLayerHostingContext):
(WebKit::WebVideoFullscreenInterfaceContext::resetMediaState):
(WebKit::WebVideoFullscreenInterfaceContext::setDuration):
(WebKit::WebVideoFullscreenInterfaceContext::setCurrentTime):
(WebKit::WebVideoFullscreenInterfaceContext::setBufferedTime):
(WebKit::WebVideoFullscreenInterfaceContext::setRate):
(WebKit::WebVideoFullscreenInterfaceContext::setVideoDimensions):
(WebKit::WebVideoFullscreenInterfaceContext::setSeekableRanges):
(WebKit::WebVideoFullscreenInterfaceContext::setCanPlayFastReverse):
(WebKit::WebVideoFullscreenInterfaceContext::setAudioMediaSelectionOptions):
(WebKit::WebVideoFullscreenInterfaceContext::setLegibleMediaSelectionOptions):
(WebKit::WebVideoFullscreenInterfaceContext::setExternalPlayback):

Cross-process methods which now take a contextId parameter:

* UIProcess/ios/WebVideoFullscreenManagerProxy.messages.in:
* UIProcess/ios/WebVideoFullscreenManagerProxy.mm:
(WebKit::WebVideoFullscreenManagerProxy::setupFullscreenWithID):
(WebKit::WebVideoFullscreenManagerProxy::resetMediaState):
(WebKit::WebVideoFullscreenManagerProxy::setCurrentTime):
(WebKit::WebVideoFullscreenManagerProxy::setBufferedTime):
(WebKit::WebVideoFullscreenManagerProxy::setVideoDimensions):
(WebKit::WebVideoFullscreenManagerProxy::setSeekableRangesVector):
(WebKit::WebVideoFullscreenManagerProxy::setCanPlayFastReverse):
(WebKit::WebVideoFullscreenManagerProxy::setAudioMediaSelectionOptions):
(WebKit::WebVideoFullscreenManagerProxy::setLegibleMediaSelectionOptions):
(WebKit::WebVideoFullscreenManagerProxy::setExternalPlaybackProperties):
(WebKit::WebVideoFullscreenManagerProxy::setDuration):
(WebKit::WebVideoFullscreenManagerProxy::setRate):
(WebKit::WebVideoFullscreenManagerProxy::exitFullscreen):
(WebKit::WebVideoFullscreenManagerProxy::cleanupFullscreen):
(WebKit::WebVideoFullscreenManagerProxy::preparedToReturnToInline):
(WebKit::WebVideoFullscreenManagerProxy::play):
(WebKit::WebVideoFullscreenManagerProxy::pause):
(WebKit::WebVideoFullscreenManagerProxy::togglePlayState):
(WebKit::WebVideoFullscreenManagerProxy::beginScrubbing):
(WebKit::WebVideoFullscreenManagerProxy::endScrubbing):
(WebKit::WebVideoFullscreenManagerProxy::seekToTime):
(WebKit::WebVideoFullscreenManagerProxy::fastSeek):
(WebKit::WebVideoFullscreenManagerProxy::beginScanningForward):
(WebKit::WebVideoFullscreenManagerProxy::beginScanningBackward):
(WebKit::WebVideoFullscreenManagerProxy::endScanning):
(WebKit::WebVideoFullscreenManagerProxy::requestExitFullscreen):
(WebKit::WebVideoFullscreenManagerProxy::didSetupFullscreen):
(WebKit::WebVideoFullscreenManagerProxy::didExitFullscreen):
(WebKit::WebVideoFullscreenManagerProxy::didEnterFullscreen):
(WebKit::WebVideoFullscreenManagerProxy::didCleanupFullscreen):
(WebKit::WebVideoFullscreenManagerProxy::setVideoLayerFrame):
(WebKit::WebVideoFullscreenManagerProxy::setVideoLayerGravity):
(WebKit::WebVideoFullscreenManagerProxy::selectAudioMediaOption):
(WebKit::WebVideoFullscreenManagerProxy::selectLegibleMediaOption):
(WebKit::WebVideoFullscreenManagerProxy::fullscreenModeChanged):
(WebKit::WebVideoFullscreenManagerProxy::fullscreenMayReturnToInline):
(WebKit::WebVideoFullscreenManagerProxy::videoLayerFrame): Deleted.
(WebKit::WebVideoFullscreenManagerProxy::videoLayerGravity): Deleted.
* WebProcess/ios/WebVideoFullscreenManager.messages.in:
* WebProcess/ios/WebVideoFullscreenManager.mm:
(WebKit::WebVideoFullscreenManager::enterVideoFullscreenForVideoElement):
(WebKit::WebVideoFullscreenManager::exitVideoFullscreenForVideoElement):
(WebKit::WebVideoFullscreenManager::resetMediaState):
(WebKit::WebVideoFullscreenManager::setDuration):
(WebKit::WebVideoFullscreenManager::setCurrentTime):
(WebKit::WebVideoFullscreenManager::setBufferedTime):
(WebKit::WebVideoFullscreenManager::setRate):
(WebKit::WebVideoFullscreenManager::setVideoDimensions):
(WebKit::WebVideoFullscreenManager::setSeekableRanges):
(WebKit::WebVideoFullscreenManager::setCanPlayFastReverse):
(WebKit::WebVideoFullscreenManager::setAudioMediaSelectionOptions):
(WebKit::WebVideoFullscreenManager::setLegibleMediaSelectionOptions):
(WebKit::WebVideoFullscreenManager::setExternalPlayback):
(WebKit::WebVideoFullscreenManager::play):
(WebKit::WebVideoFullscreenManager::pause):
(WebKit::WebVideoFullscreenManager::togglePlayState):
(WebKit::WebVideoFullscreenManager::beginScrubbing):
(WebKit::WebVideoFullscreenManager::endScrubbing):
(WebKit::WebVideoFullscreenManager::seekToTime):
(WebKit::WebVideoFullscreenManager::fastSeek):
(WebKit::WebVideoFullscreenManager::beginScanningForward):
(WebKit::WebVideoFullscreenManager::beginScanningBackward):
(WebKit::WebVideoFullscreenManager::endScanning):
(WebKit::WebVideoFullscreenManager::requestExitFullscreen):
(WebKit::WebVideoFullscreenManager::selectAudioMediaOption):
(WebKit::WebVideoFullscreenManager::selectLegibleMediaOption):
(WebKit::WebVideoFullscreenManager::fullscreenModeChanged):
(WebKit::WebVideoFullscreenManager::didSetupFullscreen):
(WebKit::WebVideoFullscreenManager::didEnterFullscreen):
(WebKit::WebVideoFullscreenManager::didExitFullscreen):
(WebKit::WebVideoFullscreenManager::didCleanupFullscreen):
(WebKit::WebVideoFullscreenManager::setVideoLayerGravityEnum):
(WebKit::WebVideoFullscreenManager::fullscreenMayReturnToInline):
(WebKit::WebVideoFullscreenManager::setVideoLayerFrameFenced):
(WebKit::WebVideoFullscreenManager::exitVideoFullscreen): Deleted.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@182914 268f45cc-cd09-0410-ab3c-d52691b4dbfc