Add callback in VideoDecoder and AudioDecoder to return decoded frames.

media/base/video_decoder.cc

 // Copyright (c) 2012 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.
 
 #include "media/base/video_decoder.h"
 
 #include "media/base/video_frame.h"
 
 namespace media {
 
 VideoDecoder::VideoDecoder() {}
 
 VideoDecoder::~VideoDecoder() {}
 
-scoped_refptr<VideoFrame> VideoDecoder::GetDecodeOutput() {
-  return NULL;
-}
-
 bool VideoDecoder::NeedsBitstreamConversion() const {
   return false;
 }
 
 bool VideoDecoder::CanReadWithoutStalling() const {
   return true;
 }
 
 int VideoDecoder::GetMaxDecodeRequests() const {
   return 1;
 }
 
 }  // namespace media