Propagate capture ntp timestamp from rtp to renderer.

Mostly the interface changes, the real implementation of ntp timestamp will come in a follow up cl.

TEST=new tests and try bots
BUG=3111
R=niklas.enbom@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/11469004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5911 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/interface/module_common_types.h

@@ -103,6 +103,8 @@ struct WebRtcRTPHeader {
   RTPHeader header;
   FrameType frameType;
   RTPTypeHeader type;
+  // NTP time of the capture time in local timebase in milliseconds.
+  int64_t ntp_time_ms;
 };
 
 class RTPFragmentationHeader {