Revert "Async DNS: Remove toggle from about:flags"

chrome/browser/about_flags.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/about_flags.h"
 
 #include <iterator>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 660 matching lines @@
                               switches::kDisableQuic)
   },
   {
     "enable-spdy4",
     IDS_FLAGS_ENABLE_SPDY4_NAME,
     IDS_FLAGS_ENABLE_SPDY4_DESCRIPTION,
     kOsAll,
     SINGLE_VALUE_TYPE(switches::kEnableSpdy4)
   },
   {
+    "enable-async-dns",
+    IDS_FLAGS_ENABLE_ASYNC_DNS_NAME,
+    IDS_FLAGS_ENABLE_ASYNC_DNS_DESCRIPTION,
+    kOsWin | kOsMac | kOsLinux | kOsCrOS,
+    ENABLE_DISABLE_VALUE_TYPE(switches::kEnableAsyncDns,
+                              switches::kDisableAsyncDns)
+  },
+  {
     "disable-media-source",
     IDS_FLAGS_DISABLE_MEDIA_SOURCE_NAME,
     IDS_FLAGS_DISABLE_MEDIA_SOURCE_DESCRIPTION,
     kOsAll,
     SINGLE_VALUE_TYPE(switches::kDisableMediaSource)
   },
   {
     "disable-encrypted-media",
     IDS_FLAGS_DISABLE_ENCRYPTED_MEDIA_NAME,
     IDS_FLAGS_DISABLE_ENCRYPTED_MEDIA_DESCRIPTION,
@@ skipping 2097 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags