Convert CNG into C++ and remove it from AudioDecoder

webrtc/modules/audio_coding/neteq/decoder_database.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.
  */
 
@@ skipping 124 matching lines @@
   // Returns the current active decoder, or NULL if no active decoder exists.
   virtual AudioDecoder* GetActiveDecoder();
 
   // Sets the active comfort noise decoder to be |rtp_payload_type|. If this
   // call results in a change of active comfort noise decoder, the previous
   // active decoder's AudioDecoder object is deleted.
   virtual int SetActiveCngDecoder(uint8_t rtp_payload_type);
 
   // Returns the current active comfort noise decoder, or NULL if no active
   // comfort noise decoder exists.
-  virtual AudioDecoder* GetActiveCngDecoder();
+  virtual CNG_dec_inst* GetActiveCngDecoder();
 
   // Returns kOK if all packets in |packet_list| carry payload types that are
   // registered in the database. Otherwise, returns kDecoderNotFound.
   virtual int CheckPayloadTypes(const PacketList& packet_list) const;
 
  private:
   typedef std::map<uint8_t, DecoderInfo> DecoderMap;
 
   DecoderMap decoders_;
   int active_decoder_;
   int active_cng_decoder_;
+  CNG_dec_inst* active_cng_dec_inst_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(DecoderDatabase);
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_DECODER_DATABASE_H_