Implement autoplay gesture override experiment.

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 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef HTMLMediaElement_h
 #define HTMLMediaElement_h
 
 #include "core/CoreExport.h"
 #include "core/dom/ActiveDOMObject.h"
 #include "core/events/GenericEventQueue.h"
+#include "core/html/AutoplayExperimentHelper.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/track/TextTrack.h"
 #include "platform/Supplementable.h"
 #include "public/platform/WebMediaPlayerClient.h"
 #include "public/platform/WebMimeRegistry.h"
 
 #if ENABLE(WEB_AUDIO)
 #include "platform/audio/AudioSourceProvider.h"
 #include "public/platform/WebAudioSourceProviderClient.h"
 #endif
@@ skipping 341 matching lines @@
     void executeDeferredLoad();
     void deferredLoadTimerFired(Timer<HTMLMediaElement>*);
 
     HTMLTrackElement* showingTrackWithSameKind(HTMLTrackElement*) const;
 
     void markCaptionAndSubtitleTracksAsUnconfigured();
 
     // This does not check user gesture restrictions.
     void playInternal();
 
-    void gesturelessInitialPlayHalted();
+    // If we are about to enter a stopped state, call this to record

[philipj_slow, 2015/08/13 10:15:40]

s/stop/pause/, media elements don't really have a concept of being stopped, and
it's easy to confuse this with HTMLMediaElement::stop(), which is something else
entirely, for ActiveDOMObject.

[liberato (no reviews please), 2015/09/01 06:54:20]

updated, and the metric names.  was trying not to modify the old enum names, but
what the heck.

+    // autoplay metrics.  If we were already in a stopped state, then
+    // this does nothing.
+    void recordMetricsIfStopping();
+    // Could stopping at this point be considered a bailout of playback?
+    // (as in, "The user really didn't want to play this").
+    bool isBailout() const;
     void autoplayMediaEncountered();
     void allowVideoRendering();
 
     void updateVolume();
     void updatePlayState();
     bool potentiallyPlaying() const;
     bool stoppedDueToErrors() const;
     bool couldPlayIfEnoughData() const;
 
     // Generally the presence of the loop attribute should be considered to mean playback
@@ skipping 15 matching lines @@
 
     void changeNetworkStateFromLoadingToIdle();
 
     const AtomicString& mediaGroup() const;
     void setMediaGroup(const AtomicString&);
     void updateMediaController();
     bool isBlocked() const;
     bool isBlockedOnMediaController() const;
     bool isAutoplaying() const { return m_autoplaying; }
 
+    void recordAutoplayMetric(AutoplayMetrics);
+
     WebMediaPlayer::CORSMode corsMode() const;
 
     // Returns the "direction of playback" value as specified in the HTML5 spec.
     enum DirectionOfPlayback { Backward, Forward };
     DirectionOfPlayback directionOfPlayback() const;
 
     // Returns the "effective playback rate" value as specified in the HTML5 spec.
     double effectivePlaybackRate() const;
 
     // Creates placeholder AudioTrack and/or VideoTrack objects when WebMemediaPlayer objects
     // advertise they have audio and/or video, but don't explicitly signal them via
     // addAudioTrack() and addVideoTrack().
     // FIXME: Remove this once all WebMediaPlayer implementations properly report their track info.
     void createPlaceholderTracksIfNecessary();
 
     // Sets the selected/enabled tracks if they aren't set before we initially
     // transition to HAVE_METADATA.
     void selectInitialTracksIfNecessary();
 
+    // Return true if and only if we require a user gesture before letting
+    // the media play.
+    bool isUserGestureRequiredForPlay() const;
+    void removeUserGestureRequirement();
+    void setInitialPlayWithoutUserGestures(bool);
+
     void audioTracksTimerFired(Timer<HTMLMediaElement>*);
 
     Timer<HTMLMediaElement> m_loadTimer;
     Timer<HTMLMediaElement> m_progressEventTimer;
     Timer<HTMLMediaElement> m_playbackProgressTimer;
     Timer<HTMLMediaElement> m_audioTracksTimer;
     RefPtrWillBeMember<TimeRanges> m_playedTimeRanges;
     OwnPtrWillBeMember<GenericEventQueue> m_asyncEventQueue;
 
     double m_playbackRate;
@@ skipping 152 matching lines @@
     };
 
     AudioSourceProviderImpl m_audioSourceProvider;
 #endif
 
     friend class MediaController;
     PersistentWillBeMember<MediaController> m_mediaController;
 
     friend class Internals;
     friend class TrackDisplayUpdateScope;
+    friend class AutoplayExperimentHelper;
+
+    AutoplayExperimentHelper m_autoplayHelper;
 
     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