Use a direct include of strings headers in ppapi/, printing/.

printing/backend/win_helper.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 PRINTING_BACKEND_WIN_HELPER_H_
 #define PRINTING_BACKEND_WIN_HELPER_H_
 
 #include <objidl.h>
 #include <winspool.h>
 #include <prntvpt.h>
 #include <xpsprint.h>
 
 #include <string>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/win/scoped_handle.h"
 #include "printing/printing_export.h"
 
 // These are helper functions for dealing with Windows Printing.
 namespace printing {
 
 struct PRINTING_EXPORT PrinterBasicInfo;
 
 class PrinterHandleTraits {
  public:
@@ skipping 99 matching lines @@
 };
 
 PRINTING_EXPORT bool InitBasicPrinterInfo(HANDLE printer,
                                           PrinterBasicInfo* printer_info);
 
 PRINTING_EXPORT std::string GetDriverInfo(HANDLE printer);
 
 }  // namespace printing
 
 #endif  // PRINTING_BACKEND_WIN_HELPER_H_