Fold AudioEncoderMutable into AudioEncoder

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

Index: webrtc/modules/audio_coding/codecs/cng/include/audio_encoder_cng.h
diff --git a/webrtc/modules/audio_coding/codecs/cng/include/audio_encoder_cng.h b/webrtc/modules/audio_coding/codecs/cng/include/audio_encoder_cng.h
index 6a1136602e0b25929666febe78fbd30ed12d6db5..4927ef74724dce68162723d132927b7e052facfb 100644
--- a/webrtc/modules/audio_coding/codecs/cng/include/audio_encoder_cng.h
+++ b/webrtc/modules/audio_coding/codecs/cng/include/audio_encoder_cng.h
@@ -25,40 +25,45 @@ class Vad;
 class AudioEncoderCng final : public AudioEncoder {
  public:
   struct Config {
-    Config();
     bool IsOk() const;
 
-    int num_channels;
-    int payload_type;
+    int num_channels = 1;
+    int payload_type = 13;
     // Caller keeps ownership of the AudioEncoder object.
-    AudioEncoder* speech_encoder;
-    Vad::Aggressiveness vad_mode;
-    int sid_frame_interval_ms;
-    int num_cng_coefficients;
+    AudioEncoder* speech_encoder = nullptr;
+    Vad::Aggressiveness vad_mode = Vad::kVadNormal;
+    int sid_frame_interval_ms = 100;
+    int num_cng_coefficients = 8;
     // The Vad pointer is mainly for testing. If a NULL pointer is passed, the
     // AudioEncoderCng creates (and destroys) a Vad object internally. If an
     // object is passed, the AudioEncoderCng assumes ownership of the Vad
     // object.
-    Vad* vad;
+    Vad* vad = nullptr;
   };
 
   explicit AudioEncoderCng(const Config& config);
-
   ~AudioEncoderCng() override;
 
+  size_t MaxEncodedBytes() const override;
   int SampleRateHz() const override;
   int NumChannels() const override;
-  size_t MaxEncodedBytes() const override;
   int RtpTimestampRateHz() const override;
   size_t Num10MsFramesInNextPacket() const override;
   size_t Max10MsFramesInAPacket() const override;
   int GetTargetBitrate() const override;
-  void SetTargetBitrate(int bits_per_second) override;
-  void SetProjectedPacketLossRate(double fraction) override;
   EncodedInfo EncodeInternal(uint32_t rtp_timestamp,
                              const int16_t* audio,
                              size_t max_encoded_bytes,
                              uint8_t* encoded) override;
+  void Reset() override;
+  bool SetFec(bool enable) override;
+  bool SetDtx(bool enable) override;
+  bool SetApplication(Application application) override;
+  bool SetMaxPlaybackRate(int frequency_hz) override;
+  void SetProjectedPacketLossRate(double fraction) override;
+  void SetTargetBitrate(int target_bps) override;
+  void SetMaxBitrate(int max_bps) override;
+  void SetMaxPayloadSize(int max_payload_size_bytes) override;
 
  private:
   // Deleter for use with scoped_ptr. E.g., use as