[Media, Autoplay] Add UMA to record autoplay source

third_party/WebKit/Source/core/html/HTMLMediaElement.h

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 469 matching lines @@
     void scheduleNotifyPlaying();
 
     void resolvePlayPromises();
     // TODO(mlamouri): this is used for cancellable tasks because we can't pass
     // parameters.
     void rejectPlayPromises();
     void rejectPlayPromises(ExceptionCode, const String&);
 
     EnumerationHistogram& showControlsHistogram() const;
 
+    void recordAutoplaySourceMetric(int source);
+
     UnthrottledTimer<HTMLMediaElement> m_loadTimer;
     UnthrottledTimer<HTMLMediaElement> m_progressEventTimer;
     UnthrottledTimer<HTMLMediaElement> m_playbackProgressTimer;
     UnthrottledTimer<HTMLMediaElement> m_audioTracksTimer;
     Member<TimeRanges> m_playedTimeRanges;
     Member<GenericEventQueue> m_asyncEventQueue;
 
     double m_playbackRate;
     double m_defaultPlaybackRate;
     NetworkState m_networkState;
@@ skipping 168 matching lines @@
 inline bool isHTMLMediaElement(const HTMLElement& element)
 {
     return isHTMLAudioElement(element) || isHTMLVideoElement(element);
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLMediaElement);
 
 } // namespace blink
 
 #endif // HTMLMediaElement_h