Disable tests failing on Win Tester bot.

chrome/browser/ui/webui/options/search_engine_manager_browsertest.js

 // 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.
 
 /**
  * TestFixture for search engine manager WebUI testing.
  * @extends {testing.Test}
  * @constructor
  */
 function SearchEngineManagerWebUITest() {}
 
 SearchEngineManagerWebUITest.prototype = {
   __proto__: testing.Test.prototype,
 
   /**
    * Browse to the search engine manager.
    */
   browsePreload: 'chrome://settings-frame/searchEngines',
 };
 
 // See crosbug.com/22673 for OS_CHROMEOS
 // See crbug.com/579666 for OS_LINUX
-GEN('#if defined(OS_CHROMEOS) || defined(OS_LINUX)');
+// See crbug.com/638884 for OS_WIN
+GEN('#if defined(OS_CHROMEOS) || defined(OS_LINUX) || defined(OS_WIN)');
 GEN('#define MAYBE_testOpenSearchEngineManager ' +
         'DISABLED_testOpenSearchEngineManager');
 GEN('#else');
 GEN('#define MAYBE_testOpenSearchEngineManager testOpenSearchEngineManager');
-GEN('#endif  // defined(OS_CHROMEOS) || defined(OS_LINUX)');
+GEN('#endif  // defined(OS_CHROMEOS) || defined(OS_LINUX) || defined(OS_WIN)');
 
 // Test opening the search engine manager has correct location.
 TEST_F('SearchEngineManagerWebUITest', 'MAYBE_testOpenSearchEngineManager',
        function() {
          assertEquals(this.browsePreload, document.location.href);
        });