Wire up transport sequence number and send time.

content/common/p2p_socket_type.h

Index: content/common/p2p_socket_type.h
diff --git a/content/common/p2p_socket_type.h b/content/common/p2p_socket_type.h
index ed77296b28de513dc2fcbacb949afd41199342bc..cf32d4013cd73cf9b62b9af75da1beb3d62e5be5 100644
--- a/content/common/p2p_socket_type.h
+++ b/content/common/p2p_socket_type.h
@@ -10,6 +10,7 @@
 
 #include <string>
 
+#include "base/time/time.h"
 #include "net/base/ip_endpoint.h"
 
 namespace content {
@@ -52,10 +53,21 @@ struct P2PHostAndIPEndPoint {
 // 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