Get the default device scale factor from monitor

ui/ui.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     'ui_resources.gypi',
@@ skipping 297 matching lines @@
         'gfx/favicon_size.cc',
         'gfx/favicon_size.h',
         'gfx/font.h',
         'gfx/font.cc',
         'gfx/font_list.h',
         'gfx/font_list.cc',
         'gfx/font_smoothing_win.cc',
         'gfx/font_smoothing_win.h',
         'gfx/gfx_paths.cc',
         'gfx/gfx_paths.h',
+        'gfx/gfx_switches.cc',
+        'gfx/gfx_switches.h',
         'gfx/image/image.cc',
         'gfx/image/image.h',
         'gfx/image/image_mac.mm',
         'gfx/image/image_skia.cc',
         'gfx/image/image_skia.h',
         'gfx/image/image_util.cc',
         'gfx/image/image_util.h',
         'gfx/insets.cc',
         'gfx/insets.h',
         'gfx/interpolated_transform.h',
@@ skipping 415 matching lines @@
                 'shutil.copyfile(\'<(ui_copy_target)\', \'<(ui_copy_dest)\'); ' \
                 'os.chmod(\'<(ui_copy_dest)\', 0700)'
               ]
             }
           ],
         },
       ],
     }],
   ],
 }