Use a direct include of strings headers in chrome/test/.

chrome/test/perf/perf_ui_test_suite.cc

 // Copyright (c) 2013 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/test/perf/perf_ui_test_suite.h"
 
 #include "base/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/path_service.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/platform_thread.h"
 #include "chrome/browser/themes/browser_theme_pack.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/test/perf/generate_profile.h"
 #include "content/public/test/test_browser_thread.h"
 
 #if defined(OS_WIN)
@@ skipping 141 matching lines @@
   content::TestBrowserThread file_thread_(BrowserThread::FILE,
                                           &message_loop_);
 
   scoped_refptr<BrowserThemePack> theme(
       BrowserThemePack::BuildFromExtension(extension.get()));
   if (!theme.get())
     LOG(FATAL) << "Failed to load theme from extension";
 
   theme->WriteToDisk(extension_base.AppendASCII("Cached Theme.pak"));
 }