Added support for sending and receiving RTCP XR packets:

- Receiver reference time report block
- DLRR report block (RFC3611).

BUG=1613
R=mflodman@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2196010

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4898 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/rtp_rtcp/source/rtcp_receiver_help.h

@@ -80,6 +80,8 @@ public:
     uint32_t ntp_frac;
     uint32_t rtp_timestamp;
 
+    uint32_t xr_originator_ssrc;
+    bool xr_dlrr_item;
     RTCPVoIPMetric*  VoIPMetric;
 
 private: