Wire up transport sequence number / send time callbacks to webrtc via libjingle.

webrtc/base/asyncpacketsocket.h

Index: webrtc/base/asyncpacketsocket.h
diff --git a/webrtc/base/asyncpacketsocket.h b/webrtc/base/asyncpacketsocket.h
index f0c221da1dec3fd4014be539224366d507fcac23..e89b077073af908e57ac8b89c0b8e122165af0ec 100644
--- a/webrtc/base/asyncpacketsocket.h
+++ b/webrtc/base/asyncpacketsocket.h
@@ -34,10 +34,11 @@ struct PacketTimeUpdateParams {
 // This structure holds meta information for the packet which is about to send
 // over network.
 struct PacketOptions {
-  PacketOptions() : dscp(DSCP_NO_CHANGE) {}
-  explicit PacketOptions(DiffServCodePoint dscp) : dscp(dscp) {}
+  PacketOptions() : dscp(DSCP_NO_CHANGE), packet_id(-1) {}
+  explicit PacketOptions(DiffServCodePoint dscp) : dscp(dscp), packet_id(-1) {}
 
   DiffServCodePoint dscp;
+  int packet_id;  // 16 bits, -1 represents "not set".
   PacketTimeUpdateParams packet_time_params;
 };
 
@@ -109,6 +110,9 @@ class AsyncPacketSocket : public sigslot::has_slots<> {
                    const SocketAddress&,
                    const PacketTime&> SignalReadPacket;
 
+  // Emitted each time a packet is sent.
+  sigslot::signal2<AsyncPacketSocket*, const SentPacket&> SignalSentPacket;
+
   // Emitted when the socket is currently able to send.
   sigslot::signal1<AsyncPacketSocket*> SignalReadyToSend;