Reland of Only compare sequence numbers from the same SSRC in ForwardErrorCorrection.

webrtc/modules/rtp_rtcp/source/flexfec_receiver.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 16 matching lines @@
 constexpr int kPacketLogIntervalMs = 10000;
 
 }  // namespace
 
 FlexfecReceiver::FlexfecReceiver(
     uint32_t ssrc,
     uint32_t protected_media_ssrc,
     RecoveredPacketReceiver* recovered_packet_receiver)
     : ssrc_(ssrc),
       protected_media_ssrc_(protected_media_ssrc),
-      erasure_code_(ForwardErrorCorrection::CreateFlexfec()),
+      erasure_code_(
+          ForwardErrorCorrection::CreateFlexfec(ssrc, protected_media_ssrc)),
       recovered_packet_receiver_(recovered_packet_receiver),
       clock_(Clock::GetRealTimeClock()),
       last_recovered_packet_ms_(-1) {
   // It's OK to create this object on a different thread/task queue than
   // the one used during main operation.
   sequence_checker_.Detach();
 }
 
 FlexfecReceiver::~FlexfecReceiver() = default;
 
@@ skipping 96 matching lines @@
           ForwardErrorCorrection::ParseSsrc(recovered_packet->pkt->data);
       LOG(LS_VERBOSE) << "Recovered media packet with SSRC: " << media_ssrc
                       << " from FlexFEC stream with SSRC: " << ssrc_ << ".";
       last_recovered_packet_ms_ = now_ms;
     }
   }
   return true;
 }
 
 }  // namespace webrtc