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

content/renderer/media/webmediaplayer_ms.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_MS_H_
 #define CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_MS_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 61 matching lines @@
   virtual void seek(double seconds);
   virtual void setRate(double rate);
   virtual void setVolume(double volume);
   virtual void setPreload(blink::WebMediaPlayer::Preload preload);
   virtual blink::WebTimeRanges buffered() const;
   virtual double maxTimeSeekable() const;
 
   // 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.
   virtual bool hasVideo() const;
   virtual bool hasAudio() const;
 
   // Dimensions of the video.
   virtual blink::WebSize naturalSize() const;
 
   // Getters of playback state.
@@ skipping 93 matching lines @@
   scoped_refptr<media::MediaLog> media_log_;
 
   scoped_ptr<MediaStreamRendererFactory> renderer_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerMS);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_MS_H_