Revert of RTCRtpReceiver.getContributingSources() added.

content/renderer/media/webrtc/rtc_rtp_contributing_source.cc

-// Copyright (c) 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 "content/renderer/media/webrtc/rtc_rtp_contributing_source.h"
-
-#include "base/logging.h"
-#include "base/time/time.h"
-#include "third_party/webrtc/base/scoped_ref_ptr.h"
-
-namespace content {
-
-RTCRtpContributingSource::RTCRtpContributingSource(
-    const webrtc::RtpSource& source)
-    : source_(source) {}
-
-RTCRtpContributingSource::~RTCRtpContributingSource() {}
-
-blink::WebRTCRtpContributingSourceType RTCRtpContributingSource::SourceType()
-    const {
-  switch (source_.source_type()) {
-    case webrtc::RtpSourceType::SSRC:
-      return blink::WebRTCRtpContributingSourceType::SSRC;
-    case webrtc::RtpSourceType::CSRC:
-      return blink::WebRTCRtpContributingSourceType::CSRC;
-    default:
-      NOTREACHED();
-      return blink::WebRTCRtpContributingSourceType::SSRC;
-  }
-}
-
-double RTCRtpContributingSource::TimestampMs() const {
-  return source_.timestamp_ms();
-}
-
-uint32_t RTCRtpContributingSource::Source() const {
-  return source_.source_id();
-}
-
-}  // namespace content