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

webrtc/voice_engine/channel.cc

 /*
  *  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 29 matching lines @@
 #include "webrtc/voice_engine/transmit_mixer.h"
 #include "webrtc/voice_engine/utility.h"
 
 #if defined(_WIN32)
 #include <Qos.h>
 #endif
 
 namespace webrtc {
 namespace voe {
 
+const int kTelephoneEventAttenuationdB = 10;
+
 class TransportFeedbackProxy : public TransportFeedbackObserver {
  public:
   TransportFeedbackProxy() : feedback_observer_(nullptr) {
     pacer_thread_.DetachFromThread();
     network_thread_.DetachFromThread();
   }
 
   void SetTransportFeedbackObserver(
       TransportFeedbackObserver* feedback_observer) {
     RTC_DCHECK(thread_checker_.CalledOnValidThread());
@@ skipping 2145 matching lines @@
   _outputGain = scaling;
   return 0;
 }
 
 int Channel::GetChannelOutputVolumeScaling(float& scaling) const {
   rtc::CritScope cs(&volume_settings_critsect_);
   scaling = _outputGain;
   return 0;
 }
 
-int Channel::SendTelephoneEventOutband(unsigned char eventCode,
-                                       int lengthMs,
-                                       int attenuationDb,
-                                       bool playDtmfEvent) {
+int Channel::SendTelephoneEventOutband(int event, int duration_ms) {
   WEBRTC_TRACE(kTraceInfo, kTraceVoice, VoEId(_instanceId, _channelId),
-               "Channel::SendTelephoneEventOutband(..., playDtmfEvent=%d)",
-               playDtmfEvent);
+               "Channel::SendTelephoneEventOutband(...)");
+  RTC_DCHECK_LE(0, event);
+  RTC_DCHECK_GE(255, event);
+  RTC_DCHECK_LE(0, duration_ms);
+  RTC_DCHECK_GE(65535, duration_ms);
   if (!Sending()) {
     return -1;
   }
 
-  _playOutbandDtmfEvent = playDtmfEvent;
+  _playOutbandDtmfEvent = false;
 
-  if (_rtpRtcpModule->SendTelephoneEventOutband(eventCode, lengthMs,
-                                                attenuationDb) != 0) {
+  if (_rtpRtcpModule->SendTelephoneEventOutband(
+      event, duration_ms, kTelephoneEventAttenuationdB) != 0) {
     _engineStatisticsPtr->SetLastError(
         VE_SEND_DTMF_FAILED, kTraceWarning,
         "SendTelephoneEventOutband() failed to send event");
     return -1;
   }
   return 0;
 }
 
 int Channel::SendTelephoneEventInband(unsigned char eventCode,
                                       int lengthMs,
@@ skipping 1407 matching lines @@
   int64_t min_rtt = 0;
   if (_rtpRtcpModule->RTT(remoteSSRC, &rtt, &avg_rtt, &min_rtt, &max_rtt) !=
       0) {
     return 0;
   }
   return rtt;
 }
 
 }  // namespace voe
 }  // namespace webrtc