Use a direct include of strings headers in ui/, part 2.

ui/base/win/shell.h

 // Copyright (c) 2011 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 UI_BASE_WIN_SHELL_H_
 #define UI_BASE_WIN_SHELL_H_
 
 #include <windows.h>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/base/ui_export.h"
 
 namespace base {
 class FilePath;
 }
 
 namespace ui {
 namespace win {
 // Open or run a file via the Windows shell. In the event that there is no
 // default application registered for the file specified by 'full_path',
@@ skipping 36 matching lines @@
                                            HWND hwnd);
 
 // Returns true if composition is available and turned on on the current
 // platform.
 UI_EXPORT bool IsAeroGlassEnabled();
 
 }  // namespace win
 }  // namespace ui
 
 #endif  // UI_BASE_WIN_SHELL_H_