Reland: Add accelerated VP9 decode infrastructure and an implementation for VA-API.

content/common/gpu/media/vaapi_video_decode_accelerator.h

Index: content/common/gpu/media/vaapi_video_decode_accelerator.h
diff --git a/content/common/gpu/media/vaapi_video_decode_accelerator.h b/content/common/gpu/media/vaapi_video_decode_accelerator.h
index 268439b96bc4dad249401bf99f5570dda48862bc..fe929381218190bbe95247e46018877db36604eb 100644
--- a/content/common/gpu/media/vaapi_video_decode_accelerator.h
+++ b/content/common/gpu/media/vaapi_video_decode_accelerator.h
@@ -73,6 +73,7 @@ class CONTENT_EXPORT VaapiVideoDecodeAccelerator
  private:
   class VaapiH264Accelerator;
   class VaapiVP8Accelerator;
+  class VaapiVP9Accelerator;
 
   // Notify the client that an error has occurred and decoding cannot continue.
   void NotifyError(Error error);
@@ -275,6 +276,7 @@ class CONTENT_EXPORT VaapiVideoDecodeAccelerator
   // Accelerators come after vaapi_wrapper_ to ensure they are destroyed first.
   scoped_ptr<VaapiH264Accelerator> h264_accelerator_;
   scoped_ptr<VaapiVP8Accelerator> vp8_accelerator_;
+  scoped_ptr<VaapiVP9Accelerator> vp9_accelerator_;
   // After *_accelerator_ to ensure correct destruction order.
   scoped_ptr<AcceleratedVideoDecoder> decoder_;