2D Canvas doesn't blend video with the destination buffer.

content/renderer/media/webmediaplayer_impl.h

Index: content/renderer/media/webmediaplayer_impl.h
diff --git a/content/renderer/media/webmediaplayer_impl.h b/content/renderer/media/webmediaplayer_impl.h
index d933302c6bd94281fa4a714f7b526fb1723dfc41..0663296dc5eb6c85a79d293ffb6968cb83c73b6b 100644
--- a/content/renderer/media/webmediaplayer_impl.h
+++ b/content/renderer/media/webmediaplayer_impl.h
@@ -91,6 +91,11 @@ class WebMediaPlayerImpl
   // Methods for painting.
   virtual void paint(blink::WebCanvas* canvas,
                      const blink::WebRect& rect,
+                     unsigned char alpha,
+                     SkXfermode::Mode mode);
+  // TODO(dshwang): remove it.
+  virtual void paint(blink::WebCanvas* canvas,
+                     const blink::WebRect& rect,
                      unsigned char alpha);
 
   // True if the loaded media has a playable video/audio track.