rtt calculation handles time go backwards

webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.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 568 matching lines @@
   return  rtcp_sender_.SetApplicationSpecificData(sub_type, name, data, length);
 }
 
 // (XR) VOIP metric.
 int32_t ModuleRtpRtcpImpl::SetRTCPVoIPMetrics(
   const RTCPVoIPMetric* voip_metric) {
   return  rtcp_sender_.SetRTCPVoIPMetrics(voip_metric);
 }
 
 void ModuleRtpRtcpImpl::SetRtcpXrRrtrStatus(bool enable) {
-  return rtcp_sender_.SendRtcpXrReceiverReferenceTime(enable);
+  rtcp_receiver_.SetRtcpXrRrtrStatus(enable);
+  rtcp_sender_.SendRtcpXrReceiverReferenceTime(enable);
 }
 
 bool ModuleRtpRtcpImpl::RtcpXrRrtrStatus() const {
   return rtcp_sender_.RtcpXrReceiverReferenceTime();
 }
 
 // TODO(asapersson): Replace this method with the one below.
 int32_t ModuleRtpRtcpImpl::DataCountersRTP(
     size_t* bytes_sent,
     uint32_t* packets_sent) const {
@@ skipping 391 matching lines @@
 void ModuleRtpRtcpImpl::RegisterSendChannelRtpStatisticsCallback(
     StreamDataCountersCallback* callback) {
   rtp_sender_.RegisterRtpStatisticsCallback(callback);
 }
 
 StreamDataCountersCallback*
     ModuleRtpRtcpImpl::GetSendChannelRtpStatisticsCallback() const {
   return rtp_sender_.GetRtpStatisticsCallback();
 }
 }  // namespace webrtc