Move code that applies to audio and video tracks into TrackBase.

Source/core/html/track/TextTrackList.cpp

 /*
  * Copyright (C) 2011, 2012 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 174 matching lines @@
         m_elementTracks.insert(index, track);
     } else if (track->trackType() == TextTrack::InBand) {
         // Insert tracks added for in-band in the media file order.
         size_t index = static_cast<InbandTextTrack*>(track.get())->inbandTrackIndex();
         m_inbandTracks.insert(index, track);
     } else
         ASSERT_NOT_REACHED();
 
     invalidateTrackIndexesAfterTrack(track.get());
 
-    ASSERT(!track->mediaElement() || track->mediaElement() == m_owner);
-    track->setMediaElement(m_owner);
+    ASSERT(!track->trackList() || track->trackList() == this);

[acolwell GONE FROM CHROMIUM, 2013/12/06 01:35:54]

"track->trackList() == this" seems a little weird. What is the case where the
track list is set already and append() is called? If the track is already part
of this list, why would we allow it to be added again?

+    track->setTrackList(this);
 
     scheduleAddTrackEvent(track.release());
 }
 
 void TextTrackList::remove(TextTrack* track)
 {
     Vector<RefPtr<TextTrack> >* tracks = 0;
     RefPtr<InbandTextTrack> inbandTrack;
 
     if (track->trackType() == TextTrack::TrackElement) {
         tracks = &m_elementTracks;
     } else if (track->trackType() == TextTrack::AddTrack) {
         tracks = &m_addTrackTracks;
     } else if (track->trackType() == TextTrack::InBand) {
         tracks = &m_inbandTracks;
         inbandTrack = static_cast<InbandTextTrack*>(track);
     } else {
         ASSERT_NOT_REACHED();
     }
 
     size_t index = tracks->find(track);
     if (index == kNotFound)
         return;
 
     invalidateTrackIndexesAfterTrack(track);
 
-    ASSERT(track->mediaElement() == m_owner);
-    track->setMediaElement(0);
+    ASSERT(track->trackList() == this);
+    track->setTrackList(0);
 
     tracks->remove(index);
 
     if (inbandTrack)
         inbandTrack->trackRemoved();
 
     scheduleRemoveTrackEvent(track);
 }
 
 bool TextTrackList::contains(TextTrack* track) const
@@ skipping 72 matching lines @@
     // interface, with the track attribute initialized to the text track's
     // TextTrack object, at the media element's textTracks attribute's
     // TextTrackList object.
     scheduleTrackEvent(EventTypeNames::removetrack, track);
 }
 
 Node* TextTrackList::owner() const
 {
     return m_owner;
 }