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

third_party/WebKit/public/platform/WebMediaPlayer.h

Index: third_party/WebKit/public/platform/WebMediaPlayer.h
diff --git a/third_party/WebKit/public/platform/WebMediaPlayer.h b/third_party/WebKit/public/platform/WebMediaPlayer.h
index dd88518fb0a277a27ae0762c2e3c46d9364c81f4..85a95762e065fcfe7aef3f770e9f3ecac0f99d5b 100644
--- a/third_party/WebKit/public/platform/WebMediaPlayer.h
+++ b/third_party/WebKit/public/platform/WebMediaPlayer.h
@@ -272,6 +272,14 @@ class WebMediaPlayer {
   // WebMediaPlayerClient::activateViewportIntersectionMonitoring().
   virtual void becameDominantVisibleContent(bool isDominant) {}
 
+  // Inform WebMediaPlayer when the element starts/stops being the effectively
+  // fullscreen video, i.e. being the fullscreen element or child of the
+  // fullscreen element, and being dominant in the viewport.
+  //
+  // TODO(zqzhang): merge with becameDominantVisibleContent(). See
+  // https://crbug.com/696211
+  virtual void setIsEffectivelyFullscreen(bool) {}
+
   virtual void enabledAudioTracksChanged(
       const WebVector<TrackId>& enabledTrackIds) {}
   // |selectedTrackId| is null if no track is selected.