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

chrome/renderer/mock_printer.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_MOCK_PRINTER_H_
 #define CHROME_RENDERER_MOCK_PRINTER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "printing/image.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebPrintScalingOption.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 struct PrintMsg_Print_Params;
 struct PrintMsg_PrintPages_Params;
 struct PrintHostMsg_DidPrintPage_Params;
 
 // A class which represents an output page used in the MockPrinter class.
@@ skipping 133 matching lines @@
 
   // Used for generating invalid settings.
   bool use_invalid_settings_;
 
   std::vector<scoped_refptr<MockPrinterPage> > pages_;
 
   DISALLOW_COPY_AND_ASSIGN(MockPrinter);
 };
 
 #endif  // CHROME_RENDERER_MOCK_PRINTER_H_