Support text track selection in video controls

Source/core/html/track/TextTrack.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  * Copyright (C) 2011, 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:
  * 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
@@ skipping 88 matching lines @@
 
     enum TextTrackType { TrackElement, AddTrack, InBand };
     TextTrackType trackType() const { return m_trackType; }
 
     int trackIndex();
     void invalidateTrackIndex();
 
     bool isRendered();
     int trackIndexRelativeToRenderedTracks();
 
+    bool isRenderable();
+
     bool hasBeenConfigured() const { return m_hasBeenConfigured; }
     void setHasBeenConfigured(bool flag) { m_hasBeenConfigured = flag; }
 
     virtual bool isDefault() const { return false; }
 
     void removeAllCues();
 
     // EventTarget methods
     virtual const AtomicString& interfaceName() const override;
     virtual ExecutionContext* executionContext() const override;
@@ skipping 25 matching lines @@
     int m_trackIndex;
     int m_renderedTrackIndex;
     bool m_hasBeenConfigured;
 };
 
 DEFINE_TRACK_TYPE_CASTS(TextTrack, TrackBase::TextTrack);
 
 } // namespace blink
 
 #endif // TextTrack_h