Let the WebMediaPlayer decide whether to use overlay video.

Source/core/html/HTMLMediaElement.h

Index: Source/core/html/HTMLMediaElement.h
diff --git a/Source/core/html/HTMLMediaElement.h b/Source/core/html/HTMLMediaElement.h
index 0c5ef93861daab8264ca155ab8504945dbfddfcd..86aebd7500da3e77b270c67a63cf43b371636755 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -211,6 +211,7 @@ public:
     bool isFullscreen() const;
     void enterFullscreen();
     void exitFullscreen();
+    virtual bool supportsOverlayFullscreenVideo() const { return false; }

[trchen, 2015/07/30 21:29:21]

"supports" feels like the implementation can do it, but we can still decide to
use it or not. I feel "useOverlayFullscreenVideo" is being less confusing?

[watk, 2015/08/03 21:47:43]

Done.

 
     bool hasClosedCaptions() const;
     bool closedCaptionsVisible() const;
@@ -545,6 +546,8 @@ private:
     bool m_isFinalizing : 1;
     bool m_initialPlayWithoutUserGestures : 1;
     bool m_autoplayMediaCounted : 1;
+    // Whether this element is in overlay fullscreen mode.
+    bool m_inOverlayFullscreenVideo : 1;
 
     PersistentWillBeMember<AudioTrackList> m_audioTracks;
     PersistentWillBeMember<VideoTrackList> m_videoTracks;