Detect change on the intersection of video and viewport.

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
@@ skipping 526 matching lines @@
   void scheduleNotifyPlaying();
   void resolveScheduledPlayPromises();
   void rejectScheduledPlayPromises();
   void rejectPlayPromises(ExceptionCode, const String&);
   void rejectPlayPromisesInternal(ExceptionCode, const String&);
 
   EnumerationHistogram& showControlsHistogram() const;
 
   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;
 
   double m_playbackRate;
   double m_defaultPlaybackRate;
   NetworkState m_networkState;
   ReadyState m_readyState;
   ReadyState m_readyStateMaximum;
   KURL m_currentSrc;
   Member<MediaStreamDescriptor> m_srcObject;
@@ skipping 163 matching lines @@
 
   Member<AutoplayExperimentHelper::Client> m_autoplayHelperClient;
   Member<AutoplayExperimentHelper> m_autoplayHelper;
   Member<AutoplayUmaHelper> m_autoplayUmaHelper;
 
   WebRemotePlaybackClient* m_remotePlaybackClient;
 
   // class AutoplayVisibilityObserver;
   Member<ElementVisibilityObserver> m_autoplayVisibilityObserver;
 
+  IntRect m_currentIntersectRect;
+  bool m_mostlyFillingViewport = false;

[ojan, 2016/11/24 00:48:33]

Put the bool up in line 653 instead with the ": 1" syntax so that it can tightly
pack with the other bools. Otherwise, this line will use 32-64 bits of memory
instead of 1. :)

[xjz, 2016/11/24 02:16:16]

Done.

+
   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