Add 2 histograms which exposes last packet sent time delta and connection duration when receiving PUBLIC_RESET.

R=dschinazi@chromium.org

Change-Id: I75ae9c95b13273ef1421b28113e11c5dd63bc59e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2366913
Commit-Queue: David Schinazi <dschinazi@chromium.org>
Reviewed-by: David Schinazi <dschinazi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800155}

Author: Fan Yang

net/quic/quic_chromium_client_session.cc

@@ -1729,6 +1729,28 @@ void QuicChromiumClientSession::OnConnectionClosed(
               ->sent_packet_manager()
               .unacked_packets()
               .GetLastPacketContent());
+
+      const quic::QuicTime last_in_flight_packet_sent_time =
+          connection()
+              ->sent_packet_manager()
+              .unacked_packets()
+              .GetLastInFlightPacketSentTime();
+      const quic::QuicTime handshake_completion_time =
+          connection()->GetStats().handshake_completion_time;
+      if (last_in_flight_packet_sent_time.IsInitialized() &&
+          handshake_completion_time.IsInitialized() &&
+          last_in_flight_packet_sent_time >= handshake_completion_time) {
+        const quic::QuicTime::Delta delay =
+            last_in_flight_packet_sent_time - handshake_completion_time;
+        UMA_HISTOGRAM_LONG_TIMES_100(
+            "Net.QuicSession."
+            "LastInFlightPacketSentTimeFromHandshakeCompletionWithPublicReset",
+            base::TimeDelta::FromMilliseconds(delay.ToMilliseconds()));
+      }
+
+      UMA_HISTOGRAM_LONG_TIMES_100(
+          "Net.QuicSession.ConnectionDurationWithPublicReset",
+          tick_clock_->NowTicks() - connect_timing_.connect_end);
     }
     if (OneRttKeysAvailable()) {
       base::HistogramBase* histogram = base::SparseHistogram::FactoryGet(

tools/metrics/histograms/histograms.xml

@@ -101671,6 +101671,13 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Net.QuicSession.ConnectionDurationWithPublicReset" units="ms"
+    expires_after="2021-05-11">
+  <owner>fayang@chromium.org</owner>
+  <owner>src/net/quic/OWNERS</owner>
+  <summary>Duration of connections received PUBLIC_RESET.</summary>
+</histogram>
+
 <histogram name="Net.QuicSession.ConnectionFlowControlBlocked"
     enum="BooleanBlocked" expires_after="2021-05-11">
   <owner>dschinazi@chromium.org</owner>
@@ -102036,6 +102043,17 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram
+    name="Net.QuicSession.LastInFlightPacketSentTimeFromHandshakeCompletionWithPublicReset"
+    units="ms" expires_after="2021-05-11">
+  <owner>fayang@chromium.org</owner>
+  <owner>src/net/quic/OWNERS</owner>
+  <summary>
+    Time from handshake completion to last packet was sent for connections
+    received PUBLIC_RESET.
+  </summary>
+</histogram>
+
 <histogram name="Net.QuicSession.LastSentPacketContentBeforePublicReset"
     units="bitfield value" expires_after="2021-05-11">
   <owner>fayang@chromium.org</owner>