Reland of SSRC and RSID may only refer to one sink each in RtpDemuxer

webrtc/call/rtp_stream_receiver_controller.h

 /*
  *  Copyright (c) 2017 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_CALL_RTP_STREAM_RECEIVER_CONTROLLER_H_
@@ skipping 20 matching lines @@
  public:
   RtpStreamReceiverController();
   ~RtpStreamReceiverController() override;
 
   // Implements RtpStreamReceiverControllerInterface.
   std::unique_ptr<RtpStreamReceiverInterface> CreateReceiver(
       uint32_t ssrc,
       RtpPacketSinkInterface* sink) override;
 
   // Thread-safe wrappers for the corresponding RtpDemuxer methods.
-  void AddSink(uint32_t ssrc, RtpPacketSinkInterface* sink) override;
+  bool AddSink(uint32_t ssrc, RtpPacketSinkInterface* sink) override;
   size_t RemoveSink(const RtpPacketSinkInterface* sink) override;
 
   // TODO(nisse): Not yet responsible for parsing.
   bool OnRtpPacket(const RtpPacketReceived& packet);
 
  private:
   class Receiver : public RtpStreamReceiverInterface {
    public:
     Receiver(RtpStreamReceiverController* controller,
              uint32_t ssrc,
@@ skipping 11 matching lines @@
   // to be called on the same thread, and OnRtpPacket to be called
   // by a single, but possibly distinct, thread. But applications not
   // using Call may have use threads differently.
   rtc::CriticalSection lock_;
   RtpDemuxer demuxer_ GUARDED_BY(&lock_);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_CALL_RTP_STREAM_RECEIVER_CONTROLLER_H_