Wire up rtcp xr target bitrate on receive side.

webrtc/modules/rtp_rtcp/source/rtcp_sender.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 946 matching lines @@
 
   SetFlag(kRtcpApp, true);
   app_sub_type_ = subType;
   app_name_ = name;
   app_data_.reset(new uint8_t[length]);
   app_length_ = length;
   memcpy(app_data_.get(), data, length);
   return 0;
 }
 
+// TODO(sprang): Remove support for VoIP metrics? (Not used in receiver.)
 int32_t RTCPSender::SetRTCPVoIPMetrics(const RTCPVoIPMetric* VoIPMetric) {
   rtc::CritScope lock(&critical_section_rtcp_sender_);
   xr_voip_metric_.emplace(*VoIPMetric);
 
   SetFlag(kRtcpAnyExtendedReports, true);
   return 0;
 }
 
 void RTCPSender::SendRtcpXrReceiverReferenceTime(bool enable) {
   rtc::CritScope lock(&critical_section_rtcp_sender_);
@@ skipping 77 matching lines @@
     // but we can't because of an incorrect warning (C4822) in MVS 2013.
   } sender(transport_, event_log_);
 
   RTC_DCHECK_LE(max_payload_length_, IP_PACKET_SIZE);
   uint8_t buffer[IP_PACKET_SIZE];
   return packet.BuildExternalBuffer(buffer, max_payload_length_, &sender) &&
          !sender.send_failure_;
 }
 
 }  // namespace webrtc