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

chrome/test/base/ui_test_utils.h

 // 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.
 
 #ifndef CHROME_TEST_BASE_UI_TEST_UTILS_H_
 #define CHROME_TEST_BASE_UI_TEST_UTILS_H_
 
 #include <map>
 #include <queue>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "chrome/browser/history/history_service.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/test/test_utils.h"
 #include "googleurl/src/gurl.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/base/window_open_disposition.h"
@@ skipping 282 matching lines @@
   std::vector<GURL> urls_;
 
   CancelableRequestConsumer consumer_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryEnumerator);
 };
 
 }  // namespace ui_test_utils
 
 #endif  // CHROME_TEST_BASE_UI_TEST_UTILS_H_