Monitor the intersection of video and viewport.

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

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.h b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
index c927eeb9db8409a3900dd725e0749b70eb442480..b8ca4c16c67bed67699e0381ef6f82a4fa5a8fcd 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
@@ -534,7 +534,7 @@ class CORE_EXPORT HTMLMediaElement : public HTMLElement,
 
   EnumerationHistogram& showControlsHistogram() const;
 
-  void onVisibilityChangedForAutoplay(bool isVisible);
+  void onVideoViewportRatioChanged(bool isVisible);
 
   UnthrottledThreadTimer<HTMLMediaElement> m_loadTimer;
   UnthrottledThreadTimer<HTMLMediaElement> m_progressEventTimer;
@@ -716,11 +716,11 @@ class CORE_EXPORT HTMLMediaElement : public HTMLElement,
   Member<AutoplayExperimentHelper::Client> m_autoplayHelperClient;
   Member<AutoplayExperimentHelper> m_autoplayHelper;
   Member<AutoplayUmaHelper> m_autoplayUmaHelper;
+  bool m_autoplayWhenVisible = false;

[miu, 2016/11/05 02:47:47]

naming nit: m_shouldAutoplayWhenVisible

[miu, 2016/11/05 02:47:47]

Is the boolean necessary? (See comment in .cpp file.)

[xjz, 2016/11/09 02:24:28]

I keeps this boolean to save a bunch of checks every time when muted video
becomes visible: state change logic + tracksAreReady + shouldAutoplay() +
!isGestureNeededForPlayback() + isHTMLVideoElement() + muted() +
autoplayMutedVideosEnabled.

[xjz, 2016/11/09 02:24:28]

Done.

 
   WebRemotePlaybackClient* m_remotePlaybackClient;
 
-  // class AutoplayVisibilityObserver;
-  Member<ElementVisibilityObserver> m_autoplayVisibilityObserver;
+  Member<ElementVisibilityObserver> m_videoViewportRatioObserver;
 
   static URLRegistry* s_mediaStreamRegistry;
 };