RtpPacketReceiver base class and OnRtpPacket, with a pre-parsed RTP packet.

webrtc/call/rtp_packet_receiver.cc

+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/call/rtp_packet_receiver.h"
+
+namespace webrtc {
+
+// static
+bool RtpPacketReceiver::UseSendSideBwe(
+    const std::vector<RtpExtension>& extensions,
+    bool transport_cc) {
+  if (!transport_cc)
+    return false;
+  for (const auto& extension : extensions) {
+    if (extension.uri == RtpExtension::kTransportSequenceNumberUri)
+      return true;
+  }
+  return false;
+}
+
+}  // namespace webrtc