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 8d40a8486d9034e30d91b410061df2382031eab1..991e8534f0544eca4f24b4302925a4729d9c2df0 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.

[scherkus (not reviewing), 2014/08/21 01:09:01]

ditto

+  virtual void paint(blink::WebCanvas* canvas,
+                     const blink::WebRect& rect,
                      unsigned char alpha);
 
   // True if the loaded media has a playable video/audio track.