Add IPv6 probe support for Windows...

chrome/browser/io_thread.cc

 // Copyright (c) 2010 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 "base/command_line.h"
 #include "base/leak_tracker.h"
 #include "base/logging.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_thread.h"
@@ skipping 22 matching lines @@
 
   // 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 {
       net::HostResolverImpl* host_resolver_impl =
           global_host_resolver->GetAsHostResolverImpl();
       if (host_resolver_impl != NULL) {
         // (optionally) Use probe to decide if support is warranted.
+        bool use_ipv6_probe = true;
 
+#if defined(OS_WIN)
         // Measure impact of probing to allow IPv6.
         // Some users report confused OS handling of IPv6, leading to large
         // latency.  If we can show that IPv6 is not supported, then disabliing
-        // it will work around such problems.
+        // it will work around such problems. This is the test of the probe.
         const FieldTrial::Probability kDivisor = 100;
         const FieldTrial::Probability kProbability = 50;  // 50% probability.
         FieldTrial* trial = new FieldTrial("IPv6_Probe", kDivisor);
         int skip_group = trial->AppendGroup("_IPv6_probe_skipped",
                                             kProbability);
         trial->AppendGroup("_IPv6_probe_done",
                            FieldTrial::kAllRemainingProbability);
-        bool use_ipv6_probe = (trial->group() != skip_group);
+        use_ipv6_probe = (trial->group() != skip_group);
+#endif
+
         if (use_ipv6_probe)
           host_resolver_impl->ProbeIPv6Support();
       }
     }
   }
 
   // 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))
@@ skipping 181 matching lines @@
     net::HostCache* host_cache =
         globals_->host_resolver.get()->GetAsHostResolverImpl()->cache();
     if (host_cache)
       host_cache->clear();
   }
   // Clear all of the passively logged data.
   // TODO(eroman): this is a bit heavy handed, really all we need to do is
   //               clear the data pertaining to off the record context.
   globals_->net_log->passive_collector()->Clear();
 }