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/video_coding/main/source/frame_buffer.cc

@@ -96,6 +96,8 @@ VCMFrameBuffer::InsertPacket(const VCMPacket& packet,
         // First packet (empty and/or media) inserted into this frame.
         // store some info and set some initial values.
         _timeStamp = packet.timestamp;
+        // We only take the ntp timestamp of the first packet of a frame.
+        ntp_time_ms_ = packet.ntp_time_ms_;
         _codec = packet.codec;
         if (packet.frameType != kFrameEmpty) {
             // first media packet