Wire up transport sequence number and send time.

content/common/p2p_socket_type.h

 // Copyright 2014 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.
 
 // This file defines some basic types used by the P2P-related IPC
 // messages.
 
 #ifndef CONTENT_COMMON_P2P_SOCKET_TYPE_H_
 #define CONTENT_COMMON_P2P_SOCKET_TYPE_H_
 
 #include <string>
 
+#include "base/time/time.h"
 #include "net/base/ip_endpoint.h"
 
 namespace content {
 
 enum P2PSocketOption {
   P2P_SOCKET_OPT_RCVBUF,  // Receive buffer size.
   P2P_SOCKET_OPT_SNDBUF,  // Send buffer size.
   P2P_SOCKET_OPT_DSCP,    // DSCP code.
   P2P_SOCKET_OPT_MAX
 };
@@ skipping 20 matching lines @@
                        const net::IPEndPoint& ip_address)
       : hostname(hostname), ip_address(ip_address) {
   }
 
   std::string hostname;
   net::IPEndPoint ip_address;
 };
 
 // Stuct which keeps track of metrics during a send operation on P2P sockets.
 // Currently, it only carries packet_id but could be expanded to include
 // timestamps when packet arrives at various points.

[no sievers, 2015/09/21 19:45:42]

nit: you might want to update the comment, or shorten it

[Stefan, 2015/09/22 07:51:36]

Significantly shortened.

 struct P2PSendPacketMetrics {
-  P2PSendPacketMetrics() : packet_id(0) {}
-  explicit P2PSendPacketMetrics(uint64_t packet_id) : packet_id(packet_id) {}
+  P2PSendPacketMetrics() {}
+  P2PSendPacketMetrics(uint64_t packet_id,
+                       int32_t transport_sequence_number,
+                       base::TimeTicks send_time)
+      : packet_id(packet_id),
+        transport_sequence_number(transport_sequence_number),
+        send_time(send_time) {}
 
-  uint64_t packet_id;
+  uint64_t packet_id = 0;
+  // Transport sequence number is a sequential packet counter written in the
+  // RTP header and used by RTP receivers to ACK received packets. It is sent
+  // back with a corresponding send time to WebRTC in the browser process so
+  // that it can be combined with ACKs to compute inter-packet delay variations.
+  int32_t transport_sequence_number = -1;
+  base::TimeTicks send_time;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_P2P_SOCKET_TYPE_H_