Remove unused TextTrack virtual functions

Source/web/InbandTextTrackPrivateImpl.h

 /*
  * 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 35 matching lines @@
                                    public WebInbandTextTrackClient {
 public:
     explicit InbandTextTrackPrivateImpl(WebInbandTextTrack*);
     virtual ~InbandTextTrackPrivateImpl();
 
     // InbandTextTrackPrivate methods.
     virtual void setMode(Mode);
     virtual InbandTextTrackPrivate::Mode mode() const;
 
     virtual Kind kind() const;
-    virtual bool isClosedCaptions() const;
 
     virtual AtomicString label() const;
     virtual AtomicString language() const;
     virtual bool isDefault() const;
 
     virtual int textTrackIndex() const;
 
     // WebInbandTextTrackClient methods.
     virtual void addWebVTTCue(double start,
                               double end,
                               const WebString& id,
                               const WebString& content,
                               const WebString& settings);
 
 private:
     WebInbandTextTrack* m_track;
 };
 
 }
 
 #endif