[gstreamer] Make sure gstreamer source element is thread-safe

https://bugs.webkit.org/show_bug.cgi?id=115352

Patch by Andre Moreira Magalhaes <andre.magalhaes@collabora.co.uk> on 2013-08-27
Reviewed by Philippe Normand.

Source/WebCore:

GStreamer source element may be created by any gstreamer element on any thread by calling
gst_element_make_from_uri with the URIs handled by the source element.
This patch makes sure the gstreamer source element is thread-safe to avoid issues with it
being created outside the main thread.

* platform/graphics/gstreamer/WebKitWebSourceGStreamer.cpp:
(webkit_web_src_init):
(webKitWebSrcDispose):
(webKitWebSrcFinalize):
(webKitWebSrcSetProperty):
(webKitWebSrcGetProperty):
(removeTimeoutSources):
(webKitWebSrcStop):
(webKitWebSrcStart):
(webKitWebSrcChangeState):
(webKitWebSrcQueryWithParent):
(webKitWebSrcGetUri):
(webKitWebSrcSetUri):
(webKitWebSrcNeedDataMainCb):
(webKitWebSrcNeedDataCb):
(webKitWebSrcEnoughDataMainCb):
(webKitWebSrcEnoughDataCb):
(webKitWebSrcSeekMainCb):
(webKitWebSrcSeekDataCb):
(webKitWebSrcSetMediaPlayer):
(StreamingClient::StreamingClient):
(StreamingClient::~StreamingClient):
(StreamingClient::createReadBuffer):
(StreamingClient::handleResponseReceived):
(StreamingClient::handleDataReceived):
(StreamingClient::handleNotifyFinished):
(CachedResourceStreamingClient::CachedResourceStreamingClient):
(CachedResourceStreamingClient::~CachedResourceStreamingClient):
(CachedResourceStreamingClient::loadFailed):
(CachedResourceStreamingClient::setDefersLoading):
(CachedResourceStreamingClient::getOrCreateReadBuffer):
(CachedResourceStreamingClient::responseReceived):
(CachedResourceStreamingClient::dataReceived):
(CachedResourceStreamingClient::notifyFinished):
(ResourceHandleStreamingClient::ResourceHandleStreamingClient):
(ResourceHandleStreamingClient::~ResourceHandleStreamingClient):
(ResourceHandleStreamingClient::loadFailed):
(ResourceHandleStreamingClient::setDefersLoading):
(ResourceHandleStreamingClient::getOrCreateReadBuffer):
(ResourceHandleStreamingClient::willSendRequest):
(ResourceHandleStreamingClient::didReceiveResponse):
(ResourceHandleStreamingClient::didReceiveData):
(ResourceHandleStreamingClient::didFinishLoading):
(ResourceHandleStreamingClient::didFail):
(ResourceHandleStreamingClient::wasBlocked):
(ResourceHandleStreamingClient::cannotShowURL):
Make element thread-safe, add support to use the element without a player associated (e.g.
the DASH plugin using the webkitsrc to download fragments), use GMutexLocker to simplify
locks and other general improvements.

Source/WTF:

Add convenience class that simplifies locking and unlocking a GMutex.

* GNUmakefile.list.am:
* wtf/gobject/GMutexLocker.h: Added.
(WebCore::GMutexLocker::GMutexLocker):
(WebCore::GMutexLocker::~GMutexLocker):
(WebCore::GMutexLocker::lock):
(WebCore::GMutexLocker::unlock):
(WebCore::GMutexLocker::mutex):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@154683 268f45cc-cd09-0410-ab3c-d52691b4dbfc