Quic: add netlog event on Key Update.

Bug: b/143909628
Change-Id: I8942a9b3f68ad5266b7d10aa3146c9cf8778e76d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2488712Reviewed-by: David Schinazi <dschinazi@chromium.org>
Commit-Queue: Matt Mueller <mattm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819211}

net/log/net_log_event_type_list.h

@@ -2247,6 +2247,12 @@ EVENT_TYPE(QUIC_SESSION_DROPPED_UNDECRYPTABLE_PACKET)
 // }
 EVENT_TYPE(QUIC_SESSION_ATTEMPTING_TO_PROCESS_UNDECRYPTABLE_PACKET)
 
+// Session has updated to the next set of 1-RTT keys.
+// {
+//   "reason": <the reason the key update was triggered>
+// }
+EVENT_TYPE(QUIC_SESSION_KEY_UPDATE)
+
 // ------------------------------------------------------------------------
 // QuicHttpStream
 // ------------------------------------------------------------------------

net/quic/quic_chromium_client_session.cc

@@ -2495,6 +2495,12 @@ void QuicChromiumClientSession::OnForwardProgressMadeAfterPathDegrading() {
     observer.OnSessionResumedPostPathDegrading(this, current_network);
 }
 
+void QuicChromiumClientSession::OnKeyUpdate(quic::KeyUpdateReason reason) {
+  net_log_.AddEventWithStringParams(NetLogEventType::QUIC_SESSION_KEY_UPDATE,
+                                    "reason",
+                                    quic::KeyUpdateReasonString(reason));
+}
+
 void QuicChromiumClientSession::OnProofValid(
     const quic::QuicCryptoClientConfig::CachedState& cached) {
   DCHECK(cached.proof_valid());

net/quic/quic_chromium_client_session.h

@@ -567,6 +567,7 @@ class NET_EXPORT_PRIVATE QuicChromiumClientSession
                         bool is_connectivity_probe) override;
   void OnPathDegrading() override;
   void OnForwardProgressMadeAfterPathDegrading() override;
+  void OnKeyUpdate(quic::KeyUpdateReason reason) override;
 
   // QuicChromiumPacketReader::Visitor methods:
   void OnReadError(int result, const DatagramClientSocket* socket) override;