Make DCHECK in QuicConnection::OnRetransmissionTimeout() more useful.

Rewrite DCHECK so that crash log shows whether handshake_mode_disabled() or
!IsHandshakeComplete() fails.

gfe-relnote: n/a (no functional change)
PiperOrigin-RevId: 297571966
Change-Id: Ifaf8e9b9ae77d5d1c1ec977d15b4696693286fdc

quic/core/quic_connection.cc

diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 4cfc95d..4f5861e 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -2613,9 +2613,13 @@
 }
 
 void QuicConnection::OnRetransmissionTimeout() {
-  DCHECK(!sent_packet_manager_.unacked_packets().empty() ||
-         (sent_packet_manager_.handshake_mode_disabled() &&
-          !IsHandshakeComplete()));
+#ifndef NDEBUG
+  if (sent_packet_manager_.unacked_packets().empty()) {
+    DCHECK(sent_packet_manager_.handshake_mode_disabled());
+    DCHECK(!IsHandshakeComplete());
+  }
+#endif
+
   const QuicPacketNumber previous_created_packet_number =
       packet_creator_.packet_number();
   if (close_connection_after_five_rtos_ &&