Revert of RTCRtpReceiver.getContributingSources() added.

third_party/WebKit/public/platform/WebRTCRtpReceiver.h

Index: third_party/WebKit/public/platform/WebRTCRtpReceiver.h
diff --git a/third_party/WebKit/public/platform/WebRTCRtpReceiver.h b/third_party/WebKit/public/platform/WebRTCRtpReceiver.h
index 02105fd0821f4d2c19931e68cefac9e514bf44a1..5852aa0f0f1ad78ee141d05ce28f25d8d6373aff 100644
--- a/third_party/WebKit/public/platform/WebRTCRtpReceiver.h
+++ b/third_party/WebKit/public/platform/WebRTCRtpReceiver.h
@@ -7,12 +7,10 @@
 
 #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
@@ -26,8 +24,6 @@
   // 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