When autoplaying muted video, record when unmute happen and the result.

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 280 matching lines @@
     void didMoveToNewDocument(Document& oldDocument) override;
     virtual KURL posterImageURL() const { return KURL(); }
 
     enum DisplayMode { Unknown, Poster, Video };
     DisplayMode getDisplayMode() const { return m_displayMode; }
     virtual void setDisplayMode(DisplayMode mode) { m_displayMode = mode; }
 
     void recordAutoplayMetric(AutoplayMetrics);
 
 private:
+    enum class AutoplayUnmuteStatus { Failure, Success };

[whywhat, 2016/06/28 10:20:59]

nit: do we really need two enums for this? this one could be a bool with the
method named recordAutoplayUnmutePausedState(bool paused) ?

Then the recordXX method would look like:

autoplayUnmuteHistogram.count(paused ? AutoplayUnmuteActionFailure :
AutoplayUnmuteActionSuccess);

[mlamouri (slow - plz ping), 2016/06/28 13:58:27]

I moved to one enum in the header used for histograms too.

+
     void resetMediaPlayerAndMediaSource();
 
     bool alwaysCreateUserAgentShadowRoot() const final { return true; }
     bool areAuthorShadowsAllowed() const final { return false; }
 
     bool supportsFocus() const final;
     bool isMouseFocusable() const final;
     bool layoutObjectIsNeeded(const ComputedStyle&) override;
     LayoutObject* createLayoutObject(const ComputedStyle&) override;
     InsertionNotificationRequest insertedInto(ContainerNode*) final;
@@ skipping 174 matching lines @@
     void scheduleRejectPlayPromises(ExceptionCode);
     void scheduleNotifyPlaying();
     void resolveScheduledPlayPromises();
     void rejectScheduledPlayPromises();
     void rejectPlayPromises(ExceptionCode, const String&);
     void rejectPlayPromisesInternal(ExceptionCode, const String&);
 
     EnumerationHistogram& showControlsHistogram() const;
 
     void recordAutoplaySourceMetric(int source);
+    void recordAutoplayUnmuteStatus(AutoplayUnmuteStatus);
 
     void onVisibilityChangedForAutoplay(bool isVisible);
 
     UnthrottledTimer<HTMLMediaElement> m_loadTimer;
     UnthrottledTimer<HTMLMediaElement> m_progressEventTimer;
     UnthrottledTimer<HTMLMediaElement> m_playbackProgressTimer;
     UnthrottledTimer<HTMLMediaElement> m_audioTracksTimer;
     Member<TimeRanges> m_playedTimeRanges;
     Member<GenericEventQueue> m_asyncEventQueue;
 
@@ skipping 176 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