Add SourceBuffer implementations of Audio/VideoTracks

third_party/WebKit/Source/core/html/track/TrackBase.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 46 matching lines @@
 #endif
 }
 
 Node* TrackBase::owner() const
 {
     return m_mediaElement;
 }
 
 DEFINE_TRACE(TrackBase)
 {
+    HeapSupplementable<TrackBase>::trace(visitor);
     visitor->trace(m_mediaElement);
 }
 
 void TrackBase::setKind(const AtomicString& kind)
 {
     if (isValidKind(kind))
         m_kind = kind;
     else
         m_kind = defaultKind();
 }
 
 } // namespace blink