Quic: Only log key update count histogram for connections that supported key update.

Bug: b/170619368
Change-Id: Ibea31679adb343c79335f884ca5675d75b252ffe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2493821Reviewed-by: David Schinazi <dschinazi@chromium.org>
Commit-Queue: Matt Mueller <mattm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820090}

net/quic/quic_chromium_client_session.cc

@@ -1869,8 +1869,10 @@ void QuicChromiumClientSession::OnConnectionClosed(
         "Net.QuicSession.ConnectionDuration",
         tick_clock_->NowTicks() - connect_timing_.connect_end);
     UMA_HISTOGRAM_COUNTS_100("Net.QuicSession.NumMigrations", num_migrations_);
-    base::UmaHistogramCounts100("Net.QuicSession.KeyUpdate.PerConnection",
-                                connection()->GetStats().key_update_count);
+    if (config()->KeyUpdateSupportedForConnection()) {
+      base::UmaHistogramCounts100("Net.QuicSession.KeyUpdate.PerConnection2",
+                                  connection()->GetStats().key_update_count);
+    }
   } else {
     if (error == quic::QUIC_PUBLIC_RESET) {
       RecordHandshakeFailureReason(HANDSHAKE_FAILURE_PUBLIC_RESET);

tools/metrics/histograms/histograms_xml/net/histograms.xml

@@ -2929,6 +2929,10 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Net.QuicSession.KeyUpdate.PerConnection" units="count"
     expires_after="2021-05-11">
+  <obsolete>
+    Replaced 2020-10-22 with Net.QuicSession.KeyUpdate.PerConnection2 that is
+    only logged for connections which supported key update.
+  </obsolete>
   <owner>mattm@chromium.org</owner>
   <owner>src/net/quic/OWNERS</owner>
   <summary>
@@ -2937,6 +2941,17 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Net.QuicSession.KeyUpdate.PerConnection2" units="count"
+    expires_after="2021-05-11">
+  <owner>mattm@chromium.org</owner>
+  <owner>src/net/quic/OWNERS</owner>
+  <summary>
+    The number of key updates processed per connection, recorded on connection
+    close. Only logged for connections which reached the 1-RTT level and
+    supported key update.
+  </summary>
+</histogram>
+
 <histogram
     name="Net.QuicSession.LastInFlightPacketSentTimeFromHandshakeCompletionWithPublicReset"
     units="ms" expires_after="2021-05-11">