Remove TextTrackClient interface to simplify TextTrack code.

Source/core/html/track/LoadableTextTrack.h

 /*
  * Copyright (C) 2011 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:
  * 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 27 matching lines @@
 class LoadableTextTrack FINAL : public TextTrack, private TextTrackLoaderClient {
 public:
     static PassRefPtr<LoadableTextTrack> create(HTMLTrackElement* track)
     {
         return adoptRef(new LoadableTextTrack(track));
     }
     virtual ~LoadableTextTrack();
 
     void scheduleLoad(const KURL&);
 
-    // This shadows TextTrack::clearClient, but need not be virtual.
-    void clearClient();
+    // TextTrack method.
+    virtual void setMode(const AtomicString&) OVERRIDE;
 
     size_t trackElementIndex();
     HTMLTrackElement* trackElement() { return m_trackElement; }
+    void clearTrackElement();
 
     virtual bool isDefault() const OVERRIDE { return m_isDefault; }
     virtual void setIsDefault(bool isDefault) OVERRIDE  { m_isDefault = isDefault; }
 
 private:
     // TextTrackLoaderClient
     virtual void newCuesAvailable(TextTrackLoader*) OVERRIDE;
     virtual void cueLoadingCompleted(TextTrackLoader*, bool loadingFailed) OVERRIDE;
     virtual void newRegionsAvailable(TextTrackLoader*) OVERRIDE;
 
     LoadableTextTrack(HTMLTrackElement*);
 
     void loadTimerFired(Timer<LoadableTextTrack>*);
 
     HTMLTrackElement* m_trackElement;
     Timer<LoadableTextTrack> m_loadTimer;
     OwnPtr<TextTrackLoader> m_loader;
     KURL m_url;
     bool m_isDefault;
 };
 } // namespace WebCore
 
 #endif