Initial implementation of AudioTrack, AudioTrackList, VideoTrack, and VideoTrackList.

Source/core/html/track/TextTrackList.cpp

Index: Source/core/html/track/TextTrackList.cpp
diff --git a/Source/core/html/track/TextTrackList.cpp b/Source/core/html/track/TextTrackList.cpp
index ba8ca1aea8f759f1a53575c5f100be8f5627e0d7..a5b09bde4d6fde5651f054eccef69fd0299caf94 100644
--- a/Source/core/html/track/TextTrackList.cpp
+++ b/Source/core/html/track/TextTrackList.cpp
@@ -198,7 +198,7 @@ void TextTrackList::append(PassRefPtr<TextTrack> prpTrack)
     scheduleAddTrackEvent(track.release());
 }
 
-void TextTrackList::remove(TextTrack* track)
+void TextTrackList::remove(TextTrack* track, bool fireRemoveTrackEvent)
 {
     Vector<RefPtr<TextTrack> >* tracks = 0;
     RefPtr<InbandTextTrack> inbandTrack;
@@ -228,7 +228,8 @@ void TextTrackList::remove(TextTrack* track)
     if (inbandTrack)
         inbandTrack->trackRemoved();
 
-    scheduleRemoveTrackEvent(track);
+    if (fireRemoveTrackEvent)
+        scheduleRemoveTrackEvent(track);
 }
 
 bool TextTrackList::contains(TextTrack* track) const
@@ -258,6 +259,14 @@ ExecutionContext* TextTrackList::executionContext() const
     return m_owner->executionContext();
 }
 
+void TextTrackList::clearOwnerAndClients()
+{
+    m_owner = 0;
+
+    for (unsigned i = 0; i < length(); ++i)
+        item(i)->clearClient();
+}
+
 void TextTrackList::scheduleTrackEvent(const AtomicString& eventName, PassRefPtr<TextTrack> track)
 {
     TrackEventInit initializer;