Log detailed information when client is about to test liveness.

PiperOrigin-RevId: 495014834

quiche/quic/core/quic_connection.cc

diff --git a/quiche/quic/core/quic_connection.cc b/quiche/quic/core/quic_connection.cc
index 85f91a5..ae2e4f0 100644
--- a/quiche/quic/core/quic_connection.cc
+++ b/quiche/quic/core/quic_connection.cc
@@ -704,6 +704,15 @@
   if (!sent_packet_manager_.IsLessThanThreePTOs(timeout)) {
     return false;
   }
+  QUIC_LOG_EVERY_N_SEC(INFO, 60)
+      << "Testing liveness, idle_network_timeout: "
+      << idle_network_detector_.idle_network_timeout()
+      << ", timeout: " << timeout
+      << ", Pto delay: " << sent_packet_manager_.GetPtoDelay()
+      << ", smoothed_rtt: "
+      << sent_packet_manager_.GetRttStats()->smoothed_rtt()
+      << ", mean deviation: "
+      << sent_packet_manager_.GetRttStats()->mean_deviation();
   SendConnectivityProbingPacket(writer_, peer_address());
   return true;
 }