Remove interface probing for IPv6 support from HostResolverImpl

chrome/browser/io_thread.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/io_thread.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 144 matching lines @@
       options.max_retry_attempts = static_cast<size_t>(n);
     } else {
       LOG(ERROR) << "Invalid switch for host resolver retry attempts: " << s;
     }
   }
 
   scoped_ptr<net::HostResolver> global_host_resolver(
       net::HostResolver::CreateSystemResolver(options, net_log));
 
   // Determine if we should disable IPv6 support.
-  if (!command_line.HasSwitch(switches::kEnableIPv6)) {
-    if (command_line.HasSwitch(switches::kDisableIPv6)) {
-      global_host_resolver->SetDefaultAddressFamily(net::ADDRESS_FAMILY_IPV4);
-    } else {
-      global_host_resolver->ProbeIPv6Support();
-    }
+  if (command_line.HasSwitch(switches::kEnableIPv6)) {
+    // Disable IPv6 probing.
+    global_host_resolver->SetDefaultAddressFamily(
+        net::ADDRESS_FAMILY_UNSPECIFIED);
+  } else if (command_line.HasSwitch(switches::kDisableIPv6)) {
+    global_host_resolver->SetDefaultAddressFamily(net::ADDRESS_FAMILY_IPV4);
   }
 
   // If hostname remappings were specified on the command-line, layer these
   // rules on top of the real host resolver. This allows forwarding all requests
   // through a designated test server.
   if (!command_line.HasSwitch(switches::kHostResolverRules))
     return global_host_resolver.PassAs<net::HostResolver>();
 
   scoped_ptr<net::MappedHostResolver> remapped_resolver(
       new net::MappedHostResolver(global_host_resolver.Pass()));
@@ skipping 785 matching lines @@
   if (command_line.HasSwitch(switches::kDisableQuic))
     return false;
 
   if (command_line.HasSwitch(switches::kEnableQuic) ||
       command_line.HasSwitch(switches::kEnableQuicHttps)) {
     return true;
   }
 
   return quic_trial_group == kQuicFieldTrialEnabledGroupName;
 }