Revert of RTCRtpReceiver.getContributingSources() added.

third_party/WebKit/Source/modules/peerconnection/RTCRtpContributingSource.cpp

-// 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.
-
-#include "modules/peerconnection/RTCRtpContributingSource.h"
-
-#include "modules/peerconnection/RTCRtpReceiver.h"
-#include "public/platform/WebRTCRtpContributingSource.h"
-
-namespace blink {
-
-RTCRtpContributingSource::RTCRtpContributingSource(
-    RTCRtpReceiver* receiver,
-    const WebRTCRtpContributingSource& webContributingSource)
-    : receiver_(receiver),
-      timestamp_ms_(webContributingSource.TimestampMs()),
-      source_(webContributingSource.Source()) {
-  DCHECK(receiver_);
-}
-
-void RTCRtpContributingSource::UpdateMembers(
-    const WebRTCRtpContributingSource& webContributingSource) {
-  timestamp_ms_ = webContributingSource.TimestampMs();
-  DCHECK_EQ(webContributingSource.Source(), source_);
-}
-
-double RTCRtpContributingSource::timestamp() {
-  receiver_->UpdateSourcesIfNeeded();
-  return timestamp_ms_;
-}
-
-uint32_t RTCRtpContributingSource::source() const {
-  // Skip |receiver_->UpdateSourcesIfNeeded()|, |source_| is a constant.
-  return source_;
-}
-
-DEFINE_TRACE(RTCRtpContributingSource) {
-  visitor->Trace(receiver_);
-}
-
-}  // namespace blink