Add MediaCodecAudioDecoder implementation

media/base/audio_decoder.h

 // 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.
 
 #ifndef MEDIA_BASE_AUDIO_DECODER_H_
 #define MEDIA_BASE_AUDIO_DECODER_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 22 matching lines @@
     kDecodeError  // A decoding error occurred.
   };
 
   // Callback for VideoDecoder initialization.
   typedef base::Callback<void(bool success)> InitCB;
 
   // Callback for AudioDecoder to return a decoded frame whenever it becomes
   // available. Only non-EOS frames should be returned via this callback.
   typedef base::Callback<void(const scoped_refptr<AudioBuffer>&)> OutputCB;
 
-  // Callback for Decode(). Called after the decoder has completed decoding
-  // corresponding DecoderBuffer, indicating that it's ready to accept another
-  // buffer to decode.
+  // Callback for Decode(). Called after the decoder has accepted corresponding
+  // DecoderBuffer, indicating that the pipeline can send next buffer to decode.
   typedef base::Callback<void(Status)> DecodeCB;
 
   AudioDecoder();
 
   // Fires any pending callbacks, stops and destroys the decoder.
   // Note: Since this is a destructor, |this| will be destroyed after this call.
   // Make sure the callbacks fired from this call doesn't post any task that
   // depends on |this|.
   virtual ~AudioDecoder();
 
@@ skipping 30 matching lines @@
   // aborted before |closure| is called.
   virtual void Reset(const base::Closure& closure) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_DECODER_H_