Reland of Create RtcpDemuxer

webrtc/call/rsid_resolution_observer.h

Index: webrtc/call/rsid_resolution_observer.h
diff --git a/webrtc/call/rsid_resolution_observer.h b/webrtc/call/rsid_resolution_observer.h
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+++ b/webrtc/call/rsid_resolution_observer.h
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+/*
+ *  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_RSID_RESOLUTION_OBSERVER_H_
+#define WEBRTC_CALL_RSID_RESOLUTION_OBSERVER_H_
+
+#include <string>
+
+#include "webrtc/base/basictypes.h"
+
+namespace webrtc {
+
+// One RSID can be associated with one, and only one, SSRC, throughout a call.
+// The resolution might either happen during call setup, or during the call.
+class RsidResolutionObserver {
+ public:
+  virtual ~RsidResolutionObserver() = default;
+
+  virtual void OnRsidResolved(const std::string& rsid, uint32_t ssrc) = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_CALL_RSID_RESOLUTION_OBSERVER_H_