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

content/renderer/media/android/webmediaplayer_android.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_ANDROID_WEBMEDIAPLAYER_ANDROID_H_
 #define CONTENT_RENDERER_MEDIA_ANDROID_WEBMEDIAPLAYER_ANDROID_H_
 
 #include <jni.h>
 #include <string>
 #include <vector>
@@ skipping 94 matching lines @@
   // Poster image, as defined in the <video> element.
   virtual void setPoster(const blink::WebURL& poster) OVERRIDE;
 
   // Methods for painting.
   // FIXME: This path "only works" on Android. It is a workaround for the
   // issue that Skia could not handle Android's GL_TEXTURE_EXTERNAL_OES texture
   // internally. It should be removed and replaced by the normal paint path.
   // https://code.google.com/p/skia/issues/detail?id=1189
   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]

it's a bit silly... but I really like having TODOs be self-explanatory at all
times -- even if you plan on fixing it soon

if you go on vacation for a month after this lands (or get busy working on
something else, etc...) the next person who sees this code will have to figure
out what your original intent was

here we should at least have a few words saying "why" and/or link to a bug that
contains more details

+  virtual void paint(blink::WebCanvas* canvas,
+                     const blink::WebRect& rect,
                      unsigned char alpha);
 
   virtual bool copyVideoTextureToPlatformTexture(
       blink::WebGraphicsContext3D* web_graphics_context,
       unsigned int texture,
       unsigned int level,
       unsigned int internal_format,
       unsigned int type,
       bool premultiply_alpha,
       bool flip_y);
@@ skipping 336 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<WebMediaPlayerAndroid> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_ANDROID_WEBMEDIAPLAYER_ANDROID_H_