Follow-up to https://codereview.chromium.org/938853002

net/quic/quic_server_bin.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // A binary wrapper for QuicServer.  It listens forever on --port
 // (default 6121) until it's killed or ctrl-cd to death.
 
 #include <iostream>
 
 #include "base/at_exit.h"
@@ skipping 30 matching lines @@
     std::cout << help_str;
     exit(0);
   }
 
   if (line->HasSwitch("quic_in_memory_cache_dir")) {
     net::g_quic_in_memory_cache_dir =
         line->GetSwitchValueNative("quic_in_memory_cache_dir");
   }
 
   if (line->HasSwitch("port")) {
-    int port;
-    if (base::StringToInt(line->GetSwitchValueASCII("port"), &port)) {
-      FLAGS_port = port;
-    } else {
+    if (!base::StringToInt(line->GetSwitchValueASCII("port"), &FLAGS_port)) {
       LOG(ERROR) << "--port must be an integer\n";
       return 1;
     }
   }
 
   base::AtExitManager exit_manager;
   base::MessageLoopForIO message_loop;
 
   net::IPAddressNumber ip;
   CHECK(net::ParseIPLiteralToNumber("::", &ip));
 
   net::QuicConfig config;
   net::QuicServer server(config, net::QuicSupportedVersions());
 
   int rc = server.Listen(net::IPEndPoint(ip, FLAGS_port));
   if (rc < 0) {
     return 1;
   }
 
   base::RunLoop().Run();
 
   return 0;
 }