Convert CNG into C++ and remove it from AudioDecoder

webrtc/modules/audio_coding/codecs/cng/audio_encoder_cng.h

 /*
  *  Copyright (c) 2014 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_CNG_AUDIO_ENCODER_CNG_H_
 #define WEBRTC_MODULES_AUDIO_CODING_CODECS_CNG_AUDIO_ENCODER_CNG_H_
 
 #include <memory>
 #include <vector>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/common_audio/vad/include/vad.h"
 #include "webrtc/modules/audio_coding/codecs/audio_encoder.h"
 #include "webrtc/modules/audio_coding/codecs/cng/webrtc_cng.h"
 
 namespace webrtc {
 
-// Deleter for use with unique_ptr.
-struct CngInstDeleter {
-  void operator()(CNG_enc_inst* ptr) const { WebRtcCng_FreeEnc(ptr); }
-};
-
 class Vad;
 
 class AudioEncoderCng final : public AudioEncoder {
  public:
   struct Config {
     Config();
     Config(Config&&);
     ~Config();
     bool IsOk() const;
 
@@ skipping 39 matching lines @@
   size_t SamplesPer10msFrame() const;
 
   std::unique_ptr<AudioEncoder> speech_encoder_;
   const int cng_payload_type_;
   const int num_cng_coefficients_;
   const int sid_frame_interval_ms_;
   std::vector<int16_t> speech_buffer_;
   std::vector<uint32_t> rtp_timestamps_;
   bool last_frame_active_;
   std::unique_ptr<Vad> vad_;
-  std::unique_ptr<CNG_enc_inst, CngInstDeleter> cng_inst_;
+  std::unique_ptr<ComfortNoiseEncoder> cng_encoder_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(AudioEncoderCng);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_CODECS_CNG_AUDIO_ENCODER_CNG_H_