Relanding https://codereview.webrtc.org/1715883002/ in pieces.

webrtc/voice_engine/channel.h

Index: webrtc/voice_engine/channel.h
diff --git a/webrtc/voice_engine/channel.h b/webrtc/voice_engine/channel.h
index 65c34f66c8059a189632784ac732fde19d161526..f1f6ba256779dd692380043b3022eec5d372f4e0 100644
--- a/webrtc/voice_engine/channel.h
+++ b/webrtc/voice_engine/channel.h
@@ -25,8 +25,6 @@
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp.h"
 #include "webrtc/modules/utility/include/file_player.h"
 #include "webrtc/modules/utility/include/file_recorder.h"
-#include "webrtc/voice_engine/dtmf_inband.h"
-#include "webrtc/voice_engine/dtmf_inband_queue.h"
 #include "webrtc/voice_engine/include/voe_audio_processing.h"
 #include "webrtc/voice_engine/include/voe_network.h"
 #include "webrtc/voice_engine/level_indicator.h"
@@ -298,12 +296,7 @@ class Channel
 
   // VoEDtmf
   int SendTelephoneEventOutband(int event, int duration_ms);
-  int SendTelephoneEventInband(unsigned char eventCode,
-                               int lengthMs,
-                               int attenuationDb,
-                               bool playDtmfEvent);
   int SetSendTelephoneEventPayloadType(unsigned char type);
-  int GetSendTelephoneEventPayloadType(unsigned char& type);
 
   // VoEAudioProcessingImpl
   int UpdateRxVadDetection(AudioFrame& audioFrame);
@@ -461,7 +454,6 @@ class Channel
   bool IsPacketInOrder(const RTPHeader& header) const;
   bool IsPacketRetransmitted(const RTPHeader& header, bool in_order) const;
   int ResendPackets(const uint16_t* sequence_numbers, int length);
-  int InsertInbandDtmfTone();
   int32_t MixOrReplaceAudioWithFile(int mixingFrequency);
   int32_t MixAudioWithFile(AudioFrame& audioFrame, int mixingFrequency);
   void UpdatePlayoutTimestamp(bool rtcp);
@@ -507,13 +499,10 @@ class Channel
   int _outputFilePlayerId;
   int _outputFileRecorderId;
   bool _outputFileRecording;
-  DtmfInbandQueue _inbandDtmfQueue;
-  DtmfInband _inbandDtmfGenerator;
   bool _outputExternalMedia;
   VoEMediaProcess* _inputExternalMediaCallbackPtr;
   VoEMediaProcess* _outputExternalMediaCallbackPtr;
   uint32_t _timeStamp;
-  uint8_t _sendTelephoneEventPayloadType;
 
   RemoteNtpTimeEstimator ntp_estimator_ GUARDED_BY(ts_stats_lock_);
 
@@ -559,7 +548,6 @@ class Channel
   float _outputGain;
   // VoEDtmf
   bool _playOutbandDtmfEvent;
-  bool _playInbandDtmfEvent;
   // VoeRTP_RTCP
   uint32_t _lastLocalTimeStamp;
   int8_t _lastPayloadType;