Disable tests failing on Win Tester bot.

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

Index: chrome/browser/ui/webui/options/search_engine_manager_browsertest.js
diff --git a/chrome/browser/ui/webui/options/search_engine_manager_browsertest.js b/chrome/browser/ui/webui/options/search_engine_manager_browsertest.js
index f0b7ddb2eafd8f83f448dbb90103722a4c5c2a0d..1576939a855e518d192db9f7f4ac495add3a5556 100644
--- a/chrome/browser/ui/webui/options/search_engine_manager_browsertest.js
+++ b/chrome/browser/ui/webui/options/search_engine_manager_browsertest.js
@@ -20,12 +20,13 @@ SearchEngineManagerWebUITest.prototype = {
 
 // 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',