Quic: Add histogram for connections that appeared to attempt a key update but failed decryption.

Bug: b/170619368
Change-Id: Id999e5a86a548e874879714e91a13a9475cf3c1c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2503549
Commit-Queue: Matt Mueller <mattm@chromium.org>
Commit-Queue: David Schinazi <dschinazi@chromium.org>
Auto-Submit: Matt Mueller <mattm@chromium.org>
Reviewed-by: David Schinazi <dschinazi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821398}

net/quic/quic_chromium_client_session.cc

@@ -1895,6 +1895,9 @@ void QuicChromiumClientSession::OnConnectionClosed(
     if (config()->KeyUpdateSupportedForConnection()) {
       base::UmaHistogramCounts100("Net.QuicSession.KeyUpdate.PerConnection2",
                                   connection()->GetStats().key_update_count);
+      base::UmaHistogramCounts100(
+          "Net.QuicSession.KeyUpdate.PotentialPeerKeyUpdateAttemptCount",
+          connection()->PotentialPeerKeyUpdateAttemptCount());
       if (last_key_update_reason_ != quic::KeyUpdateReason::kInvalid) {
         std::string suffix =
             last_key_update_reason_ == quic::KeyUpdateReason::kRemote ? "Remote"

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

@@ -2952,6 +2952,18 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Net.QuicSession.KeyUpdate.PotentialPeerKeyUpdateAttemptCount"
+    units="count" expires_after="2021-05-11">
+  <owner>mattm@chromium.org</owner>
+  <owner>src/net/quic/OWNERS</owner>
+  <summary>
+    Count of packets received that appeared to attempt a key update but failed
+    decryption which have been received since the last successfully decrypted
+    packet, recorded on connection close. Only logged for connections which
+    reached the 1-RTT level and supported key update.
+  </summary>
+</histogram>
+
 <histogram name="Net.QuicSession.KeyUpdate.Reason" enum="QuicKeyUpdateReason"
     expires_after="2021-05-11">
   <owner>mattm@chromium.org</owner>