[net] Add AsyncDns field trial.

chrome/chrome_browser.gypi

 # 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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
@@ skipping 1482 matching lines @@
         'browser/metrics/metrics_service.cc',
         'browser/metrics/metrics_service.h',
         'browser/metrics/thread_watcher.cc',
         'browser/metrics/thread_watcher.h',
         'browser/metrics/tracking_synchronizer.cc',
         'browser/metrics/tracking_synchronizer.h',
         'browser/metrics/tracking_synchronizer_observer.h',
         'browser/metrics/variations/variations_service.cc',
         'browser/metrics/variations/variations_service.h',
         'browser/native_window_notification_source.h',
+        'browser/net/async_dns_field_trial.cc',
+        'browser/net/async_dns_field_trial.h',
         'browser/net/chrome_cookie_notification_details.h',
         'browser/net/chrome_fraudulent_certificate_reporter.cc',
         'browser/net/chrome_fraudulent_certificate_reporter.h',
         'browser/net/chrome_net_log.cc',
         'browser/net/chrome_net_log.h',
         'browser/net/chrome_network_delegate.cc',
         'browser/net/chrome_network_delegate.h',
         'browser/net/chrome_url_request_context.cc',
         'browser/net/chrome_url_request_context.h',
         'browser/net/clear_on_exit_policy.cc',
@@ skipping 4107 matching lines @@
           'includes': [ '../build/jni_generator.gypi' ],
           'dependencies': [
             'android_jar_jni_headers',
           ],
         },
       ],
      },
     ],
   ],
 }