Implement DataCue interface.

Source/core/html/track/TextTrackCue.h

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2012, 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 61 matching lines @@
 
     int cueIndex();
     void invalidateCueIndex();
 
     using EventTarget::dispatchEvent;
     virtual bool dispatchEvent(PassRefPtrWillBeRawPtr<Event>) OVERRIDE;
 
     bool isActive();
     void setIsActive(bool);
 
-    virtual void updateDisplay(const IntSize& videoSize, HTMLDivElement& container) = 0;
+    virtual void updateDisplay(const IntSize& videoSize, HTMLDivElement& container) { };
 
     // FIXME: Consider refactoring to eliminate or merge the following three members.
     // https://code.google.com/p/chromium/issues/detail?id=322434
-    virtual void updateDisplayTree(double movieTime) = 0;
-    virtual void removeDisplayTree() = 0;
-    virtual void notifyRegionWhenRemovingDisplayTree(bool notifyRegion) = 0;
+    virtual void updateDisplayTree(double movieTime) { };
+    virtual void removeDisplayTree() { };
+    virtual void notifyRegionWhenRemovingDisplayTree(bool notifyRegion) { };
+
+    enum CueType { WebVTT, Data };
+    virtual CueType cueType() const = 0;
 
     virtual const AtomicString& interfaceName() const OVERRIDE;
 
 #ifndef NDEBUG
     virtual String toString() const = 0;
 #endif
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(enter);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(exit);
 
@@ skipping 13 matching lines @@
 
     RawPtrWillBeMember<TextTrack> m_track;
 
     bool m_isActive : 1;
     bool m_pauseOnExit : 1;
 };
 
 } // namespace WebCore
 
 #endif