Update Decryptor interface to support audio decoding.

media/base/mock_filters.cc

Index: media/base/mock_filters.cc
diff --git a/media/base/mock_filters.cc b/media/base/mock_filters.cc
index 9f02cb32d9759b851ea0615dc7c66f8f106fdece..249e531424ed4ce35bd3e0165ed19d782690f1bc 100644
--- a/media/base/mock_filters.cc
+++ b/media/base/mock_filters.cc
@@ -44,6 +44,13 @@ MockDecryptor::MockDecryptor() {}
 
 MockDecryptor::~MockDecryptor() {}
 
+void MockDecryptor::InitializeAudioDecoder(
+    scoped_ptr<AudioDecoderConfig> config,
+    const DecoderInitCB& init_cb,
+    const KeyAddedCB& key_added_cb) {
+  InitializeAudioDecoderMock(*config, init_cb, key_added_cb);
+}
+
 void MockDecryptor::InitializeVideoDecoder(
     scoped_ptr<VideoDecoderConfig> config,
     const DecoderInitCB& init_cb,