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

webrtc/modules/rtp_rtcp/source/fec_test_helper.h

 /*
  *  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 31 matching lines @@
         ssrc_(ssrc),
         random_(random) {}
 
   // Construct the media packets, up to |num_media_packets| packets.
   ForwardErrorCorrection::PacketList ConstructMediaPackets(
       int num_media_packets,
       uint16_t start_seq_num);
   ForwardErrorCorrection::PacketList ConstructMediaPackets(
       int num_media_packets);
 
-  uint16_t GetFecSeqNum();
+  uint16_t GetNextSeqNum();
 
  private:
   uint32_t min_packet_size_;
   uint32_t max_packet_size_;
   uint32_t ssrc_;
   Random* random_;
 
   ForwardErrorCorrection::PacketList media_packets_;
-  uint16_t fec_seq_num_;
+  uint16_t next_seq_num_;
 };
 
 // This class generates media packets with a certain structure of the payload.
 class AugmentedPacketGenerator {
  public:
   explicit AugmentedPacketGenerator(uint32_t ssrc);
 
   // Prepare for generating a new set of packets, corresponding to a frame.
   void NewFrame(size_t num_packets);
 
@@ skipping 53 matching lines @@
   static void SetRedHeader(uint8_t payload_type,
                            size_t header_length,
                            AugmentedPacket* red_packet);
 };
 
 }  // namespace fec
 }  // namespace test
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_FEC_TEST_HELPER_H_