Only compare sequence numbers from the same SSRC in ForwardErrorCorrection.

webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.cc

Index: webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.cc
diff --git a/webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.cc b/webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.cc
index 2752a378c9fa8fed18486905a38e367083b31335..1226117c32d72f3408834c8d00645895d35a0cf1 100644
--- a/webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.cc
+++ b/webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.cc
@@ -90,6 +90,7 @@ int32_t UlpfecReceiverImpl::AddReceivedRedPacket(
   // Get payload type from RED header and sequence number from RTP header.
   uint8_t payload_type = incoming_rtp_packet[header.headerLength] & 0x7f;
   received_packet->is_fec = payload_type == ulpfec_payload_type;
+  received_packet->ssrc = header.ssrc;
   received_packet->seq_num = header.sequenceNumber;
 
   uint16_t block_length = 0;
@@ -155,6 +156,7 @@ int32_t UlpfecReceiverImpl::AddReceivedRedPacket(
     second_received_packet->pkt = new ForwardErrorCorrection::Packet;
 
     second_received_packet->is_fec = true;
+    second_received_packet->ssrc = header.ssrc;
     second_received_packet->seq_num = header.sequenceNumber;
     ++packet_counter_.num_fec_packets;