Wire up BitrateAllocation to be sent as RTCP TargetBitrate

webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h

 /*
  *  Copyright (c) 2012 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.
  */
 
@@ skipping 84 matching lines @@
   kRtcpSrReq = 0x0400,
   kRtcpXrVoipMetric = 0x0800,
   kRtcpApp = 0x1000,
   kRtcpSli = 0x4000,
   kRtcpRpsi = 0x8000,
   kRtcpRemb = 0x10000,
   kRtcpTransmissionTimeOffset = 0x20000,
   kRtcpXrReceiverReferenceTime = 0x40000,
   kRtcpXrDlrrReportBlock = 0x80000,
   kRtcpTransportFeedback = 0x100000,
+  kRtcpXrTargetBitrate = 0x200000,
+  kRtcpAnyExtendedReports = kRtcpXrVoipMetric | kRtcpXrReceiverReferenceTime |
+                            kRtcpXrDlrrReportBlock |
+                            kRtcpXrTargetBitrate

[stefan-webrtc, 2016/12/01 08:42:20]

This looks a bit odd. Should this really belong to RTCPPacketType?

[sprang_webrtc, 2016/12/01 10:47:58]

The problem is in rtcp sender, it becomes either rather complicated or we'll
have to change the type in a number of places from enum to uint32_t... I would
have liked to rather go the other way (to an enum class) in the not too distant
future. 

I'll change to an uint32_t for now and remove this. Let's keep the  refactorings
to separate cls.

 };
 
 enum KeyFrameRequestMethod { kKeyFrameReqPliRtcp, kKeyFrameReqFirRtcp };
 
 enum RtpRtcpPacketType { kPacketRtp = 0, kPacketKeepAlive = 1 };
 
 enum RetransmissionMode : uint8_t {
   kRetransmitOff = 0x0,
   kRetransmitFECPackets = 0x1,
   kRetransmitBaseLayer = 0x2,
@@ skipping 281 matching lines @@
 class TransportSequenceNumberAllocator {
  public:
   TransportSequenceNumberAllocator() {}
   virtual ~TransportSequenceNumberAllocator() {}
 
   virtual uint16_t AllocateSequenceNumber() = 0;
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_INCLUDE_RTP_RTCP_DEFINES_H_