Replace AudioDecoderConfig with simple accessors on AudioDecoder.

media/base/mock_filters.h

Index: media/base/mock_filters.h
diff --git a/media/base/mock_filters.h b/media/base/mock_filters.h
index e2151860c89851c81f8618c2fcf60dd62b0a11d4..8abcbd33b43977c9d9676004b01a3faeedab8edd 100644
--- a/media/base/mock_filters.h
+++ b/media/base/mock_filters.h
@@ -212,8 +212,10 @@ class MockAudioDecoder : public AudioDecoder {
   MOCK_METHOD3(Initialize, void(DemuxerStream* stream,
                                 FilterCallback* callback,
                                 StatisticsCallback* stats_callback));
-  MOCK_METHOD0(config, AudioDecoderConfig());
   MOCK_METHOD1(ProduceAudioSamples, void(scoped_refptr<Buffer>));
+  MOCK_METHOD0(bits_per_channel, int(void));
+  MOCK_METHOD0(channel_layout, ChannelLayout(void));
+  MOCK_METHOD0(sample_rate, int(void));
 
   void ConsumeAudioSamplesForTest(scoped_refptr<Buffer> buffer) {
     AudioDecoder::ConsumeAudioSamples(buffer);