Add a PacketOptions struct to webrtc::Transport.

webrtc/transport.h

 /*
  *  Copyright (c) 2013 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.
  */
 
 #ifndef WEBRTC_VIDEO_ENGINE_NEW_INCLUDE_TRANSPORT_H_
 #define WEBRTC_VIDEO_ENGINE_NEW_INCLUDE_TRANSPORT_H_
 
 #include <stddef.h>
 
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
+struct PacketOptions {
+  // A 16 bits positive id. Negative ids are invalid and should be interpreted
+  // as packet_id not being set.
+  int packet_id = -1;
+};
+
 class Transport {
  public:
-  virtual bool SendRtp(const uint8_t* packet, size_t length) = 0;
+  virtual bool SendRtp(const uint8_t* packet,
+                       size_t length,
+                       const PacketOptions& options) = 0;
   virtual bool SendRtcp(const uint8_t* packet, size_t length) = 0;
 
  protected:
   virtual ~Transport() {}
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_ENGINE_NEW_INCLUDE_TRANSPORT_H_