Remove --enable-ipv6 and --disable-ipv6 command line flags.

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/base64.h"
 #include "base/bind.h"
@@ skipping 179 matching lines @@
   scoped_ptr<net::HostResolver> global_host_resolver;
 #if defined OS_CHROMEOS
   global_host_resolver =
       chromeos::HostResolverImplChromeOS::CreateSystemResolver(options,
                                                                net_log);
 #else
   global_host_resolver =
       net::HostResolver::CreateSystemResolver(options, net_log);
 #endif
 
-  // Determine if we should disable IPv6 support.
-  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.Pass();
 
   scoped_ptr<net::MappedHostResolver> remapped_resolver(
       new net::MappedHostResolver(global_host_resolver.Pass()));
   remapped_resolver->SetRulesFromString(
       command_line.GetSwitchValueASCII(switches::kHostResolverRules));
@@ skipping 1397 matching lines @@
   net::QuicVersionVector supported_versions = net::QuicSupportedVersions();
   for (size_t i = 0; i < supported_versions.size(); ++i) {
     net::QuicVersion version = supported_versions[i];
     if (net::QuicVersionToString(version) == quic_version) {
       return version;
     }
   }
 
   return net::QUIC_VERSION_UNSUPPORTED;
 }