Let PacketRouter separate send and receive modules.

webrtc/modules/pacing/packet_router.h

 /*
  *  Copyright (c) 2015 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_PACING_PACKET_ROUTER_H_
 #define WEBRTC_MODULES_PACING_PACKET_ROUTER_H_
 
 #include <list>
+#include <vector>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/common_types.h"
 #include "webrtc/modules/pacing/paced_sender.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 
 namespace webrtc {
 
 class RtpRtcp;
 namespace rtcp {
 class TransportFeedback;
 }  // namespace rtcp
 
-// PacketRouter routes outgoing data to the correct sending RTP module, based
-// on the simulcast layer in RTPVideoHeader.
+// PacketRouter keeps track of rtp send modules to support the pacer.
+// In addition, it handles feedback messages, which are sent on a send
+// module if possible (sender report), otherwise on receive module
+// (receiver report). For the latter case, we also keep track of the
+// receive modules.
 class PacketRouter : public PacedSender::PacketSender,
                      public TransportSequenceNumberAllocator {
  public:
   PacketRouter();
   virtual ~PacketRouter();
 
-  void AddRtpModule(RtpRtcp* rtp_module);
-  void RemoveRtpModule(RtpRtcp* rtp_module);
+  // TODO(nisse): Delete, as soon as downstream app is updated.
+  RTC_DEPRECATED void AddRtpModule(RtpRtcp* rtp_module) {
+    AddReceiveRtpModule(rtp_module);
+  }
+  RTC_DEPRECATED void RemoveRtpModule(RtpRtcp* rtp_module) {
+    RemoveReceiveRtpModule(rtp_module);
+  }
+  void AddSendRtpModule(RtpRtcp* rtp_module);
+  void RemoveSendRtpModule(RtpRtcp* rtp_module);
+
+  void AddReceiveRtpModule(RtpRtcp* rtp_module);
+  void RemoveReceiveRtpModule(RtpRtcp* rtp_module);
 
   // Implements PacedSender::Callback.
   bool TimeToSendPacket(uint32_t ssrc,
                         uint16_t sequence_number,
                         int64_t capture_timestamp,
                         bool retransmission,
                         const PacedPacketInfo& packet_info) override;
 
   size_t TimeToSendPadding(size_t bytes,
                            const PacedPacketInfo& packet_info) override;
 
   void SetTransportWideSequenceNumber(uint16_t sequence_number);
   uint16_t AllocateSequenceNumber() override;
 
   // Send transport feedback packet to send-side.
   virtual bool SendFeedback(rtcp::TransportFeedback* packet);
 
  private:
   rtc::ThreadChecker pacer_thread_checker_;
   rtc::CriticalSection modules_crit_;
-  std::list<RtpRtcp*> rtp_modules_ GUARDED_BY(modules_crit_);
+  std::list<RtpRtcp*> rtp_send_modules_ GUARDED_BY(modules_crit_);
+  std::vector<RtpRtcp*> rtp_receive_modules_ GUARDED_BY(modules_crit_);
 
   volatile int transport_seq_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(PacketRouter);
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_PACING_PACKET_ROUTER_H_