Added kNotAProbe definiton to PacketInfo.

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 260 matching lines @@
              uint16_t sequence_number,
              size_t payload_size,
              int probe_cluster_id)
       : creation_time_ms(creation_time_ms),
         arrival_time_ms(arrival_time_ms),
         send_time_ms(send_time_ms),
         sequence_number(sequence_number),
         payload_size(payload_size),
         probe_cluster_id(probe_cluster_id) {}
 
+  static constexpr int kNotAProbe = -1;

[nisse-webrtc, 2017/02/17 14:49:04]

It would have been appropriate with a TODO saying how and when to delete this.
But I hope you can get rid of it reasonably soon?

+
   // Time corresponding to when this object was created.
   int64_t creation_time_ms;
   // Time corresponding to when the packet was received. Timestamped with the
   // receiver's clock.
   int64_t arrival_time_ms;
   // Time corresponding to when the packet was sent, timestamped with the
   // sender's clock.
   int64_t send_time_ms;
   // Packet identifier, incremented with 1 for every packet generated by the
   // sender.
@@ skipping 102 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_