Reland of TCRtpReceiver.getContributingSources() added.

third_party/WebKit/public/platform/WebRTCRtpReceiver.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebRTCRtpReceiver_h
 #define WebRTCRtpReceiver_h
 
 #include "WebCommon.h"
 #include "WebString.h"
+#include "WebVector.h"
 
 namespace blink {
 
 class WebMediaStreamTrack;
+class WebRTCRtpContributingSource;
 
 // Implementations of this interface keep the corresponding WebRTC-layer
 // receiver alive through reference counting. Multiple |WebRTCRtpReceiver|s
 // could reference the same receiver, see |id|.
 // https://w3c.github.io/webrtc-pc/#rtcrtpreceiver-interface
 class BLINK_PLATFORM_EXPORT WebRTCRtpReceiver {
  public:
   virtual ~WebRTCRtpReceiver();
 
   // Two |WebRTCRtpReceiver|s referencing the same WebRTC-layer receiver have
   // the same |id|.
   virtual uintptr_t Id() const = 0;
   virtual const WebMediaStreamTrack& Track() const = 0;
+  virtual WebVector<std::unique_ptr<WebRTCRtpContributingSource>>
+  GetSources() = 0;
 };
 
 }  // namespace blink
 
 #endif  // WebRTCRtpReceiver_h