Use the win32 device scale factor in Chrome ASH on Windows.

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>
@@ skipping 215 matching lines @@
   // The actual window behind the view surface.
   HWND core_window_hwnd_;
 
   // UI message loop to allow message passing into this thread.
   base::MessageLoopForUI ui_loop_;
 
   // For IME support.
   scoped_ptr<metro_driver::InputSource> input_source_;
   scoped_ptr<metro_driver::TextService> text_service_;
 
-  // The device scale factor.
-  float scale_;
+  // The metro device scale factor as reported by the winrt interfaces.
+  float metro_dpi_scale_;
+  // The win32 dpi scale which is queried via GetDeviceCaps. Please refer to
+  // ui/gfx/win/dpi.cc for more information.
+  float win32_dpi_scale_;
 };
 
 #endif  // WIN8_METRO_DRIVER_CHROME_APP_VIEW_ASH_H_