Remove interface probing for IPv6 support from HostResolverImpl

chrome/browser/net/connection_tester.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/net/connection_tester.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
@@ skipping 141 matching lines @@
         net::HostResolver::CreateSystemResolver(options, NULL /* NetLog */));
 
     // Modify it slightly based on the experiment being run.
     switch (experiment) {
       case ConnectionTester::HOST_RESOLVER_EXPERIMENT_PLAIN:
         break;
       case ConnectionTester::HOST_RESOLVER_EXPERIMENT_DISABLE_IPV6:
         resolver->SetDefaultAddressFamily(net::ADDRESS_FAMILY_IPV4);
         break;
       case ConnectionTester::HOST_RESOLVER_EXPERIMENT_IPV6_PROBE: {
-        // Note that we don't use impl->ProbeIPv6Support() since that finishes
-        // asynchronously and may not take effect in time for the test.
-        // So instead we will probe synchronously (might take 100-200 ms).
-        net::AddressFamily family = net::TestIPv6Support().ipv6_supported ?
-            net::ADDRESS_FAMILY_UNSPECIFIED : net::ADDRESS_FAMILY_IPV4;
-        resolver->SetDefaultAddressFamily(family);
+        // The system HostResolver will probe by default.
         break;
       }
       default:
         NOTREACHED();
         return net::ERR_UNEXPECTED;
     }
     host_resolver->swap(resolver);
     return net::OK;
   }
 
@@ skipping 356 matching lines @@
 
   // Notify the delegate of completion.
   delegate_->OnCompletedConnectionTestExperiment(current, result);
 
   if (remaining_experiments_.empty()) {
     delegate_->OnCompletedConnectionTestSuite();
   } else {
     StartNextExperiment();
   }
 }