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

webrtc/p2p/base/faketransportcontroller.h

Index: webrtc/p2p/base/faketransportcontroller.h
diff --git a/webrtc/p2p/base/faketransportcontroller.h b/webrtc/p2p/base/faketransportcontroller.h
index 961728d96d114938fcfd94a8bf00231ea4d15ad6..c17667346df8f83fa231718efceb7a1643811b6a 100644
--- a/webrtc/p2p/base/faketransportcontroller.h
+++ b/webrtc/p2p/base/faketransportcontroller.h
@@ -208,6 +208,8 @@ class FakeTransportChannel : public TransportChannelImpl,
     } else {
       rtc::Thread::Current()->Send(this, 0, packet);
     }
+    rtc::SentPacket sent_packet(options.packet_id, rtc::Time());
+    SignalSentPacket(this, sent_packet);
     return static_cast<int>(len);
   }
   int SetOption(rtc::Socket::Option opt, int value) override { return true; }