Make FlexFEC packets paceable through RTPSender.

webrtc/modules/rtp_rtcp/source/rtp_sender_video.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 257 matching lines @@
   return overhead;
 }
 
 void RTPSenderVideo::SetFecParameters(const FecProtectionParams& delta_params,
                                       const FecProtectionParams& key_params) {
   rtc::CritScope cs(&crit_);
   delta_fec_params_ = delta_params;
   key_fec_params_ = key_params;
 }
 
+rtc::Optional<uint32_t> RTPSenderVideo::FlexfecSsrc() const {
+  if (flexfec_sender_) {
+    return rtc::Optional<uint32_t>(flexfec_sender_->Ssrc());
+  }
+  return rtc::Optional<uint32_t>();  // No value.
+}
+
 bool RTPSenderVideo::SendVideo(RtpVideoCodecTypes video_type,
                                FrameType frame_type,
                                int8_t payload_type,
                                uint32_t rtp_timestamp,
                                int64_t capture_time_ms,
                                const uint8_t* payload_data,
                                size_t payload_size,
                                const RTPFragmentationHeader* fragmentation,
                                const RTPVideoHeader* video_header) {
   RTC_DCHECK_CALLED_SEQUENTIALLY(&encoder_checker_);
@@ skipping 124 matching lines @@
   rtc::CritScope cs(&crit_);
   return retransmission_settings_;
 }
 
 void RTPSenderVideo::SetSelectiveRetransmissions(uint8_t settings) {
   rtc::CritScope cs(&crit_);
   retransmission_settings_ = settings;
 }
 
 }  // namespace webrtc