Reland of TCRtpReceiver.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