Revert of RTCRtpReceiver.getContributingSources() added.

third_party/WebKit/public/platform/WebRTCRtpContributingSource.h

Index: third_party/WebKit/public/platform/WebRTCRtpContributingSource.h
diff --git a/third_party/WebKit/public/platform/WebRTCRtpContributingSource.h b/third_party/WebKit/public/platform/WebRTCRtpContributingSource.h
deleted file mode 100644
index 69910672ba3a7a152433570d87643e06ddc85eb5..0000000000000000000000000000000000000000
--- a/third_party/WebKit/public/platform/WebRTCRtpContributingSource.h
+++ /dev/null
@@ -1,29 +0,0 @@
-// 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 WebRTCRtpContributingSource_h
-#define WebRTCRtpContributingSource_h
-
-#include "WebCommon.h"
-
-namespace blink {
-
-enum class WebRTCRtpContributingSourceType {
-  SSRC,
-  CSRC,
-};
-
-// https://w3c.github.io/webrtc-pc/#dom-rtcrtpcontributingsource
-class BLINK_PLATFORM_EXPORT WebRTCRtpContributingSource {
- public:
-  virtual ~WebRTCRtpContributingSource();
-
-  virtual WebRTCRtpContributingSourceType SourceType() const = 0;
-  virtual double TimestampMs() const = 0;
-  virtual uint32_t Source() const = 0;
-};
-
-}  // namespace blink
-
-#endif  // WebRTCRtpContributingSource_h