Use a direct include of strings headers in url/, win8/.

win8/metro_driver/chrome_app_view_ash.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 WIN8_METRO_DRIVER_CHROME_APP_VIEW_ASH_H_
 #define WIN8_METRO_DRIVER_CHROME_APP_VIEW_ASH_H_
 
 #include <windows.applicationmodel.core.h>
 #include <windows.ui.core.h>
 #include <windows.ui.input.h>
 #include <windows.ui.viewmanagement.h>
 
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/base/events/event_constants.h"
 #include "win8/metro_driver/direct3d_helper.h"
 
 namespace IPC {
   class Listener;
   class ChannelProxy;
 }
 
 class OpenFilePickerSession;
 class SaveFilePickerSession;
@@ skipping 121 matching lines @@
   IPC::ChannelProxy* ui_channel_;
 
   // The actual window behind the view surface.
   HWND core_window_hwnd_;
 
   // UI message loop to allow message passing into this thread.
   base::MessageLoop ui_loop_;
 };
 
 #endif  // WIN8_METRO_DRIVER_CHROME_APP_VIEW_ASH_H_