Detect change on 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 0bd98bca6d30fa8ac49f065ddad4b715583cedbb..2959f6aaa849522907d9c76985140dc2f9662510 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
@@ -334,6 +334,9 @@ class CORE_EXPORT HTMLMediaElement : public HTMLElement,
   void recordAutoplayMetric(AutoplayMetrics);
 
  private:
+  // Friend class for testing.
+  friend class MediaElementFillingViewportTest;
+
   void resetMediaPlayerAndMediaSource();
 
   bool alwaysCreateUserAgentShadowRoot() const final { return true; }
@@ -544,10 +547,14 @@ class CORE_EXPORT HTMLMediaElement : public HTMLElement,
 
   void onVisibilityChangedForAutoplay(bool isVisible);
 
+  void checkViewportIntersectionChanged();
+  void viewportFillDebouncerTimerFired(TimerBase*);
+
   UnthrottledThreadTimer<HTMLMediaElement> m_loadTimer;
   UnthrottledThreadTimer<HTMLMediaElement> m_progressEventTimer;
   UnthrottledThreadTimer<HTMLMediaElement> m_playbackProgressTimer;
   UnthrottledThreadTimer<HTMLMediaElement> m_audioTracksTimer;
+  UnthrottledThreadTimer<HTMLMediaElement> m_viewportFillDebouncerTimer;
   Member<TimeRanges> m_playedTimeRanges;
   Member<GenericEventQueue> m_asyncEventQueue;
 
@@ -647,6 +654,8 @@ class CORE_EXPORT HTMLMediaElement : public HTMLElement,
   // Whether this element is in overlay fullscreen mode.
   bool m_inOverlayFullscreenVideo : 1;
 
+  bool m_mostlyFillingViewport : 1;
+
   TraceWrapperMember<AudioTrackList> m_audioTracks;
   TraceWrapperMember<VideoTrackList> m_videoTracks;
   TraceWrapperMember<TextTrackList> m_textTracks;
@@ -731,6 +740,8 @@ class CORE_EXPORT HTMLMediaElement : public HTMLElement,
   // class AutoplayVisibilityObserver;
   Member<ElementVisibilityObserver> m_autoplayVisibilityObserver;
 
+  IntRect m_currentIntersectRect;
+
   static URLRegistry* s_mediaStreamRegistry;
 };