Introduce AudioDecoderConfig to migrate away from GetAVStream().

media/base/mock_filters.h

 // Copyright (c) 2011 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.
 //
 // A new breed of mock media filters, this time using gmock!  Feel free to add
 // actions if you need interesting side-effects (i.e., copying data to the
 // buffer passed into MockDataSource::Read()).
 //
 // Don't forget you can use StrictMock<> and NiceMock<> if you want the mock
 // filters to fail the test or do nothing when an unexpected method is called.
@@ skipping 141 matching lines @@
 };
 
 class MockDemuxerStream : public DemuxerStream {
  public:
   MockDemuxerStream();
 
   // DemuxerStream implementation.
   MOCK_METHOD0(type, Type());
   MOCK_METHOD1(Read, void(const ReadCallback& read_callback));
   MOCK_METHOD0(GetAVStream, AVStream*());
+  MOCK_METHOD0(audio_decoder_config, AudioDecoderConfig*());
   MOCK_METHOD0(EnableBitstreamConverter, void());
 
  protected:
   virtual ~MockDemuxerStream();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockDemuxerStream);
 };
 
 class MockVideoDecoder : public VideoDecoder {
@@ skipping 179 matching lines @@
  public:
   MockStatisticsCallback();
   ~MockStatisticsCallback();
 
   MOCK_METHOD1(OnStatistics, void(const media::PipelineStatistics& statistics));
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MOCK_FILTERS_H_