Move AudioDecoder and related stuff to the api/ directory

webrtc/api/audio_codecs/audio_decoder.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_DECODER_H_
-#define WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_DECODER_H_
+#ifndef WEBRTC_API_AUDIO_CODECS_AUDIO_DECODER_H_
+#define WEBRTC_API_AUDIO_CODECS_AUDIO_DECODER_H_
 
 #include <memory>
 #include <vector>
 
 #include "webrtc/base/array_view.h"
 #include "webrtc/base/buffer.h"
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/optional.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
-// This is the interface class for decoders in NetEQ. Each codec type will have
-// and implementation of this class.
 class AudioDecoder {
  public:
   enum SpeechType {
     kSpeech = 1,
-    kComfortNoise = 2
+    kComfortNoise = 2,
   };
 
   // Used by PacketDuration below. Save the value -1 for errors.
   enum { kNotImplemented = -2 };
 
   AudioDecoder() = default;
   virtual ~AudioDecoder() = default;
 
   class EncodedAudioFrame {
    public:
@@ skipping 127 matching lines @@
                                       size_t encoded_len,
                                       int sample_rate_hz,
                                       int16_t* decoded,
                                       SpeechType* speech_type);
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
 };
 
 }  // namespace webrtc
-#endif  // WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_DECODER_H_
+#endif  // WEBRTC_API_AUDIO_CODECS_AUDIO_DECODER_H_