Add histograms to record QUIC Min and Smoothed RTT.

net/quic/chromium/quic_connection_logger.cc

Index: net/quic/chromium/quic_connection_logger.cc
diff --git a/net/quic/chromium/quic_connection_logger.cc b/net/quic/chromium/quic_connection_logger.cc
index aa3318c3c245aff93443943e94ba8abac8d2c9f4..df5c499b5b812c37b72fc3d8f39a4021d728d63f 100644
--- a/net/quic/chromium/quic_connection_logger.cc
+++ b/net/quic/chromium/quic_connection_logger.cc
@@ -327,6 +327,12 @@ QuicConnectionLogger::~QuicConnectionLogger() {
   UMA_HISTOGRAM_COUNTS("Net.QuicSession.HeadersStream.EarlyFramesReceived",
                        session_->headers_stream()->num_early_frames_received());
 
+  const QuicConnectionStats& stats = session_->connection()->GetStats();
+  UMA_HISTOGRAM_TIMES("Net.QuicSession.MinRTT",
+                      base::TimeDelta::FromMicroseconds(stats.min_rtt_us));
+  UMA_HISTOGRAM_TIMES("Net.QuicSession.SmoothedRTT",
+                      base::TimeDelta::FromMicroseconds(stats.srtt_us));
+
   if (num_frames_received_ > 0) {
     int duplicate_stream_frame_per_thousand =
         num_duplicate_frames_received_ * 1000 / num_frames_received_;