Eliminate MediaPlayer & MediaPlayerClient abstractions (fullscreen apis)

Source/platform/graphics/media/MediaPlayer.h

Index: Source/platform/graphics/media/MediaPlayer.h
diff --git a/Source/platform/graphics/media/MediaPlayer.h b/Source/platform/graphics/media/MediaPlayer.h
index a8fe49d367c14ebd28f49e5a63658ed121bc9d25..a4d7ccdcac9f7590937e4603dd97d7403416489c 100644
--- a/Source/platform/graphics/media/MediaPlayer.h
+++ b/Source/platform/graphics/media/MediaPlayer.h
@@ -149,10 +149,6 @@ public:
     enum Preload { None, MetaData, Auto };
     virtual void setPreload(Preload) = 0;
 
-    virtual void showFullscreenOverlay() = 0;
-    virtual void hideFullscreenOverlay() = 0;
-    virtual bool canShowFullscreenOverlay() const = 0;
-
     virtual bool hasSingleSecurityOrigin() const = 0;
 
     // Time value in the movie's time scale. It is only necessary to override this if the media