Earlier check for nullptr.

net/quic/quic_connection.cc

Index: net/quic/quic_connection.cc
diff --git a/net/quic/quic_connection.cc b/net/quic/quic_connection.cc
index 5c9ec0e4e3fc14c7d4d3b11adf4eb6f6f9fc2055..e8767b15c43b830a67c6d383ceaefcd6be4b078e 100644
--- a/net/quic/quic_connection.cc
+++ b/net/quic/quic_connection.cc
@@ -1986,11 +1986,11 @@ void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
     return;
   }
   connected_ = false;
+  DCHECK(visitor_ != nullptr);
+  visitor_->OnConnectionClosed(error, from_peer);
   if (debug_visitor_ != nullptr) {
     debug_visitor_->OnConnectionClosed(error, from_peer);
   }
-  DCHECK(visitor_ != nullptr);
-  visitor_->OnConnectionClosed(error, from_peer);
   // Cancel the alarms so they don't trigger any action now that the
   // connection is closed.
   ack_alarm_->Cancel();