Start autoplay muted videos with autoplay attribute when they are visible.

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 29 matching lines @@
 #include "public/platform/WebAudioSourceProviderClient.h"
 #include "public/platform/WebMediaPlayerClient.h"
 #include "public/platform/WebMimeRegistry.h"
 
 namespace blink {
 
 class AudioSourceProviderClient;
 class AudioTrackList;
 class ContentType;
 class CueTimeline;
+class ElementVisibilityObserver;
 class EnumerationHistogram;
 class Event;
 class ExceptionState;
 class HTMLSourceElement;
 class HTMLTrackElement;
 class KURL;
 class MediaControls;
 class MediaError;
 class MediaStreamDescriptor;
 class HTMLMediaSource;
@@ skipping 420 matching lines @@
     void scheduleNotifyPlaying();
     void resolveScheduledPlayPromises();
     void rejectScheduledPlayPromises();
     void rejectPlayPromises(ExceptionCode, const String&);
     void rejectPlayPromisesInternal(ExceptionCode, const String&);
 
     EnumerationHistogram& showControlsHistogram() const;
 
     void recordAutoplaySourceMetric(int source);
 
+    void visibilityChangedForAutoplay(bool visibility);
+
     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 157 matching lines @@
     friend class Internals;
     friend class TrackDisplayUpdateScope;
     friend class AutoplayExperimentHelper;
     friend class MediaControlsTest;
 
     Member<AutoplayExperimentHelper::Client> m_autoplayHelperClient;
     Member<AutoplayExperimentHelper> m_autoplayHelper;
 
     WebRemotePlaybackClient* m_remotePlaybackClient;
 
+    // class AutoplayVisibilityObserver;
+    Member<ElementVisibilityObserver> m_autoplayVisibilityObserver;
+
     static URLRegistry* s_mediaStreamRegistry;
 };
 
 inline bool isHTMLMediaElement(const HTMLElement& element)
 {
     return isHTMLAudioElement(element) || isHTMLVideoElement(element);
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLMediaElement);
 
 } // namespace blink
 
 #endif // HTMLMediaElement_h