Don't allocate any RTPSender object for a receive only RtpRtcp module

webrtc/call/flexfec_receive_stream_impl.cc

 /*
  *  Copyright (c) 2016 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 120 matching lines @@
       receiver_(MaybeCreateFlexfecReceiver(config_, recovered_packet_receiver)),
       rtp_receive_statistics_(
           ReceiveStatistics::Create(Clock::GetRealTimeClock())),
       rtp_rtcp_(CreateRtpRtcpModule(rtp_receive_statistics_.get(),
                                     config_.rtcp_send_transport,
                                     rtt_stats)),
       process_thread_(process_thread) {
   LOG(LS_INFO) << "FlexfecReceiveStreamImpl: " << config_.ToString();
 
   // RTCP reporting.
-  rtp_rtcp_->SetSendingMediaStatus(false);
   rtp_rtcp_->SetRTCPStatus(config_.rtcp_mode);
   rtp_rtcp_->SetSSRC(config_.local_ssrc);
   process_thread_->RegisterModule(rtp_rtcp_.get(), RTC_FROM_HERE);
 }
 
 FlexfecReceiveStreamImpl::~FlexfecReceiveStreamImpl() {
   LOG(LS_INFO) << "~FlexfecReceiveStreamImpl: " << config_.ToString();
   Stop();
   process_thread_->DeRegisterModule(rtp_rtcp_.get());
 }
@@ skipping 31 matching lines @@
   started_ = false;
 }
 
 // TODO(brandtr): Implement this member function when we have designed the
 // stats for FlexFEC.
 FlexfecReceiveStreamImpl::Stats FlexfecReceiveStreamImpl::GetStats() const {
   return FlexfecReceiveStream::Stats();
 }
 
 }  // namespace webrtc