Add the last_sent_packet_id to the candidate pair change signal

webrtc/base/networkroute.h

Index: webrtc/base/networkroute.h
diff --git a/webrtc/base/networkroute.h b/webrtc/base/networkroute.h
index dcf9015cf72ba9a1b0b72ae05360de7b8e9f2701..95c1c088ac1b59241d7ed96373a7012d9cd463e1 100644
--- a/webrtc/base/networkroute.h
+++ b/webrtc/base/networkroute.h
@@ -21,16 +21,24 @@ struct NetworkRoute {
   bool connected;
   uint16_t local_network_id;
   uint16_t remote_network_id;
+  int last_sent_packet_id;  // Last packet id sent on the PREVIOUS route.

[pthatcher1, 2016/03/30 19:34:43]

Can we use an Optional<uint16_t>?

[honghaiz3, 2016/03/30 19:48:23]

Since packet_id in the PacketOption has already used -1 (32bit) to indicate the
unset value and this value is coped from there, it is better for us to use the
same convention. Otherwise, we will have to convert that passed in 32 bits to 16
bit optional and perhaps need to check whether the passed in value is unset or
not. 

 
   NetworkRoute()
-      : connected(false), local_network_id(0), remote_network_id(0) {}
+      : connected(false),
+        local_network_id(0),
+        remote_network_id(0),
+        last_sent_packet_id(-1) {}
 
   // The route is connected if the local and remote network ids are provided.
-  NetworkRoute(uint16_t local_net_id, uint16_t remote_net_id)
+  NetworkRoute(uint16_t local_net_id,
+               uint16_t remote_net_id,
+               int last_packet_id)
       : connected(true),
         local_network_id(local_net_id),
-        remote_network_id(remote_net_id) {}
+        remote_network_id(remote_net_id),
+        last_sent_packet_id(last_packet_id) {}
 
+  // |last_sent_packet_id| does not affect the NetworkRoute comparison.
   bool operator==(const NetworkRoute& nr) const {
     return connected == nr.connected &&
            local_network_id == nr.local_network_id &&