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

talk/media/webrtc/webrtcvideoengine2.h

Index: talk/media/webrtc/webrtcvideoengine2.h
diff --git a/talk/media/webrtc/webrtcvideoengine2.h b/talk/media/webrtc/webrtcvideoengine2.h
index 52282a634f617428018f6517d47e871e8d2425d6..ce184cc3299b468003dd0aec68d03f9e93cfab64 100644
--- a/talk/media/webrtc/webrtcvideoengine2.h
+++ b/talk/media/webrtc/webrtcvideoengine2.h
@@ -188,6 +188,7 @@ class WebRtcVideoChannel2 : public rtc::MessageHandler,
                         const rtc::PacketTime& packet_time) override;
   void OnRtcpReceived(rtc::Buffer* packet,
                       const rtc::PacketTime& packet_time) override;
+  void OnPacketSent(const rtc::SentPacket& packet_sent) override;
   void OnReadyToSend(bool ready) override;
   void SetInterface(NetworkInterface* iface) override;
   void UpdateAspectRatio(int ratio_w, int ratio_h) override;