Use a direct include of strings headers in ui/, part 3.

ui/views/win/hwnd_message_handler.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 UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 #define UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 
 #include <atlbase.h>
 #include <atlapp.h>
 #include <atlmisc.h>
 #include <windows.h>
 
 #include <set>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/win/win_util.h"
 #include "ui/base/accessibility/accessibility_types.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/base/win/window_impl.h"
 #include "ui/gfx/rect.h"
 #include "ui/views/ime/input_method_delegate.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
 class Canvas;
@@ skipping 424 matching lines @@
 
   // True the first time nccalc is called on a sizable widget
   bool is_first_nccalc_;
 
   DISALLOW_COPY_AND_ASSIGN(HWNDMessageHandler);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_