Add stats for frequency offset when converting RTP timestamp to NTP time.

webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h

Index: webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h
diff --git a/webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h b/webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h
index 207e749a02a00560b3973a643b14f66e7e8bf273..cab488f3eab74251c2da7d4025e0826e2675e7b5 100644
--- a/webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h
+++ b/webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h
@@ -43,7 +43,7 @@ class RemoteNtpTimeEstimator {
  private:
   Clock* clock_;
   std::unique_ptr<TimestampExtrapolator> ts_extrapolator_;
-  RtcpList rtcp_list_;
+  RtcpMeasurements rtcp_list_;
   int64_t last_timing_log_ms_;
   RTC_DISALLOW_COPY_AND_ASSIGN(RemoteNtpTimeEstimator);
 };