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

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index e89a41526a186b0bf5ca22e08df28f2b4303d728..cb9f69ef49b1f4688ca39fb6c031bdcd623e207d 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -197,15 +197,6 @@ scoped_ptr<net::HostResolver> CreateGlobalHostResolver(net::NetLog* net_log) {
       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.