Add path for recovered packets from internal::Call to RtpStreamReceiver.

webrtc/modules/rtp_rtcp/include/flexfec_receiver.h

 /*
  *  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.
  */
 
 #ifndef WEBRTC_MODULES_RTP_RTCP_INCLUDE_FLEXFEC_RECEIVER_H_
 #define WEBRTC_MODULES_RTP_RTCP_INCLUDE_FLEXFEC_RECEIVER_H_
 
 #include <memory>
 
 #include "webrtc/base/basictypes.h"
 #include "webrtc/modules/rtp_rtcp/include/fec_receiver.h"
 
 namespace webrtc {
 
-// Callback interface for packets recovered by FlexFEC.
+// Callback interface for packets recovered by FlexFEC. The implementation
+// should be able to demultiplex the recovered RTP packets based on SSRC.
 class RecoveredPacketReceiver {
  public:
   virtual bool OnRecoveredPacket(const uint8_t* packet, size_t length) = 0;
 
  protected:
   virtual ~RecoveredPacketReceiver() = default;
 };
 
 class FlexfecReceiver {
  public:
   static std::unique_ptr<FlexfecReceiver> Create(
       uint32_t flexfec_ssrc,
       uint32_t protected_media_ssrc,
       RecoveredPacketReceiver* callback);
   virtual ~FlexfecReceiver();
 
   // Inserts a received packet (can be either media or FlexFEC) into the
   // internal buffer, and sends the received packets to the erasure code.
   // All newly recovered packets are sent back through the callback.
   virtual bool AddAndProcessReceivedPacket(const uint8_t* packet,
                                            size_t packet_length) = 0;
 
   // Returns a counter describing the added and recovered packets.
   virtual FecPacketCounter GetPacketCounter() const = 0;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_RTP_RTCP_INCLUDE_FLEXFEC_RECEIVER_H_