V4L2SVDA: Add a VP9Accelerator implementation utilizing the V4L2 VP9 frame API.

media/gpu/accelerated_video_decoder.h

 // Copyright 2015 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 MEDIA_GPU_ACCELERATED_VIDEO_DECODER_H_
 #define MEDIA_GPU_ACCELERATED_VIDEO_DECODER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 26 matching lines @@
 
   enum DecodeResult {
     kDecodeError,  // Error while decoding.
     // TODO(posciak): unsupported streams are currently treated as error
     // in decoding; in future it could perhaps be possible to fall back
     // to software decoding instead.
     // kStreamError,  // Error in stream.
     kAllocateNewSurfaces,  // Need a new set of surfaces to be allocated.
     kRanOutOfStreamData,   // Need more stream data to proceed.
     kRanOutOfSurfaces,     // Waiting for the client to free up output surfaces.
+    kNeedContextUpdate,    // Waiting for the client to update decoding context
+                           // with data acquired from the accelerator.
   };
 
   // Try to decode more of the stream, returning decoded frames asynchronously.
   // Return when more stream is needed, when we run out of free surfaces, when
   // we need a new set of them, or when an error occurs.
   virtual DecodeResult Decode() WARN_UNUSED_RESULT = 0;
 
   // Return dimensions/required number of output surfaces that client should
   // be ready to provide for the decoder to function properly.
   // To be used after Decode() returns kAllocateNewSurfaces.
   virtual gfx::Size GetPicSize() const = 0;
   virtual size_t GetRequiredNumOfPictures() const = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AcceleratedVideoDecoder);
 };
 
 }  //  namespace media
 
 #endif  // MEDIA_GPU_ACCELERATED_VIDEO_DECODER_H_