[Media Controls] Add UMA for timeline scrubber

third_party/WebKit/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 161 matching lines @@
   bool willRespondToMouseMoveEvents() override { return true; }
   void defaultEventHandler(Event*) override;
   bool containsRelatedTarget(Event*);
 
   // Methods called by MediaControlsMediaEventListener.
   void onVolumeChange();
   void onFocusIn();
   void onTimeUpdate();
   void onDurationChange();
   void onPlay();
+  void onPlaying();
   void onPause();
   void onTextTracksAddedOrRemoved();
   void onTextTracksChanged();
   void onError();
   void onLoadedMetadata();
   void onEnteredFullscreen();
   void onExitedFullscreen();
 
   // Internal cast related methods.
   void startedCasting();
@@ skipping 41 matching lines @@
   IntSize m_size;
 
   bool m_keepShowingUntilTimerFires : 1;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(MediaControls, isMediaControls());
 
 }  // namespace blink
 
 #endif