Implement <video controls> dodging for text track layout

Source/core/html/shadow/MediaControls.h

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011, 2012 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
@@ skipping 52 matching lines @@
     void enteredFullscreen();
     void exitedFullscreen();
 
     void startedCasting();
     void stoppedCasting();
     void refreshCastButtonVisibility();
     void showOverlayCastButton();
 
     void mediaElementFocused();
 
+    // Returns the layout object for the part of the controls that should be
+    // used for overlap checking during text track layout. May be null.
+    LayoutObject* layoutObjectForTextTrackLayout();
+
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit MediaControls(HTMLMediaElement&);
 
     void initializeControls();
 
     void makeOpaque();
     void makeTransparent();
 
@@ skipping 46 matching lines @@
     unsigned m_hideTimerBehaviorFlags;
     bool m_isMouseOverControls : 1;
     bool m_isPausedForScrubbing : 1;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(MediaControls, isMediaControls());
 
 }
 
 #endif