[Blink>Media] Add heuristic for dominant video detection for Android

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

 /*
  * 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 107 matching lines @@
 namespace blink {
 
 using namespace HTMLNames;
 
 using WeakMediaElementSet = HeapHashSet<WeakMember<HTMLMediaElement>>;
 using DocumentElementSetMap =
     HeapHashMap<WeakMember<Document>, Member<WeakMediaElementSet>>;
 
 namespace {
 
-constexpr float kMostlyFillViewportThreshold = 0.85f;
+constexpr float kMostlyFillViewportThresholdInDominantDimension = 0.85f;
+constexpr float kMostlyFillViewportThresholdForTargetVisibleRatio = 0.75f;
 constexpr double kMostlyFillViewportBecomeStableSeconds = 5;
 constexpr double kCheckViewportIntersectionIntervalSeconds = 1;
 
 enum MediaControlsShow {
   MediaControlsShowAttribute = 0,
   MediaControlsShowFullscreen,
   MediaControlsShowNoScript,
   MediaControlsShowNotShown,
   MediaControlsShowMax
 };
@@ skipping 3963 matching lines @@
                                 shouldReportRootBounds);
   geometry.computeGeometry();
   IntRect intersectRect = geometry.intersectionIntRect();
   if (m_currentIntersectRect == intersectRect)
     return;
 
   m_currentIntersectRect = intersectRect;
   // Reset on any intersection change, since this indicates the user is
   // scrolling around in the document, the document is changing layout, etc.
   m_viewportFillDebouncerTimer.stop();
-  bool isMostlyFillingViewport =
-      (m_currentIntersectRect.size().area() >
-       kMostlyFillViewportThreshold * geometry.rootIntRect().size().area());
+
+  bool isMostlyFillingViewport = computeIsMostlyFillingViewport(
+      geometry.targetIntRect(), geometry.rootIntRect(),
+      geometry.intersectionIntRect());
   if (m_mostlyFillingViewport == isMostlyFillingViewport)
     return;
 
   if (!isMostlyFillingViewport) {
     m_mostlyFillingViewport = isMostlyFillingViewport;
     if (m_webMediaPlayer)
       m_webMediaPlayer->becameDominantVisibleContent(m_mostlyFillingViewport);
     return;
   }
 
   m_viewportFillDebouncerTimer.startOneShot(
       kMostlyFillViewportBecomeStableSeconds, BLINK_FROM_HERE);
 }
 
 void HTMLMediaElement::viewportFillDebouncerTimerFired(TimerBase*) {
   m_mostlyFillingViewport = true;
   if (m_webMediaPlayer)
     m_webMediaPlayer->becameDominantVisibleContent(m_mostlyFillingViewport);
 }
 
+bool HTMLMediaElement::computeIsMostlyFillingViewport(
+    const IntRect& targetRect,
+    const IntRect& rootRect,
+    const IntRect& intersectionRect) {
+  if (targetRect.size().area() == 0 ||
+      intersectionRect.size().area() <=
+          kMostlyFillViewportThresholdForTargetVisibleRatio *
+              targetRect.size().area()) {
+    return false;
+  }
+
+  float xOccupationRatio = 1.0f * intersectionRect.width() / rootRect.width();
+  float yOccupationRatio = 1.0f * intersectionRect.height() / rootRect.height();

[mlamouri (slow - plz ping), 2017/02/15 11:08:04]

nit: I guess those can be `const float`

[Zhiqiang Zhang (Slow), 2017/02/15 11:52:09]

Done.

+
+  return std::max(xOccupationRatio, yOccupationRatio) >=
+         kMostlyFillViewportThresholdInDominantDimension;
+}
+
 }  // namespace blink