[oilpan] Figure out lifetime of remaining Node raw pointers (Part 2)

Source/core/html/track/TextTrackList.h

 /*
  * 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 80 matching lines @@
     virtual EventTargetData* ensureEventTargetData() { return &m_eventTargetData; }
 
     void scheduleAddTrackEvent(PassRefPtr<TextTrack>);
     void asyncEventTimerFired(Timer<TextTrackList>*);
 
     void invalidateTrackIndexesAfterTrack(TextTrack*);
 
     // FIXME(oilpan): This is a weak pointer.
     ScriptExecutionContext* m_context;
     // FIXME(oilpan): This is a strong pointer.
+    // TextTrackList and HTMLMediaElement should die together.
+    // See comment #18 of https://codereview.chromium.org/23451042/ for more details.
     HTMLMediaElement* m_owner;
 
     Vector<RefPtr<Event> > m_pendingEvents;
     Timer<TextTrackList> m_pendingEventTimer;
 
     EventTargetData m_eventTargetData;
     Vector<RefPtr<TextTrack> > m_addTrackTracks;
     Vector<RefPtr<TextTrack> > m_elementTracks;
     Vector<RefPtr<TextTrack> > m_inbandTracks;
 
     int m_dispatchingEvents;
 };
 
 } // namespace WebCore
 
 #endif