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

chrome/renderer/spellchecker/hunspell_engine.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_RENDERER_SPELLCHECKER_HUNSPELL_ENGINE_H_
 #define CHROME_RENDERER_SPELLCHECKER_HUNSPELL_ENGINE_H_
 
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/common/spellcheck_common.h"
 #include "chrome/renderer/spellchecker/spelling_engine.h"
 
 class Hunspell;
 
 namespace base {
 class MemoryMappedFile;
 }
 
@@ skipping 27 matching lines @@
   // The value indicates whether we should request a
   // dictionary from the browser when the render view asks us to check the
   // spelling of a word.
   bool initialized_;
 
   // This flags is true if we have requested dictionary.
   bool dictionary_requested_;
 };
 
 #endif  // CHROME_RENDERER_SPELLCHECKER_HUNSPELL_ENGINE_H_