Do not use assets for Ash window control button backgrounds

ash/ash.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,
     # These files lists are shared with the GN build.
     'ash_sources': [
       'accelerators/accelerator_commands.cc',
@@ skipping 15 matching lines @@
       'accelerators/magnifier_key_scroller.cc',
       'accelerators/magnifier_key_scroller.h',
       'accelerators/nested_accelerator_delegate.cc',
       'accelerators/nested_accelerator_delegate.h',
       'accelerators/spoken_feedback_toggler.cc',
       'accelerators/spoken_feedback_toggler.h',
       'accessibility_delegate.h',
       'ash_constants.cc',
       'ash_constants.h',
       'ash_export.h',
+      'ash_layout_constants.cc',
+      'ash_layout_constants.h',
       'ash_switches.cc',
       'ash_switches.h',
       'ash_touch_exploration_manager_chromeos.cc',
       'ash_touch_exploration_manager_chromeos.h',
       'audio/sounds.cc',
       'audio/sounds.h',
       'autoclick/autoclick_controller.cc',
       'autoclick/autoclick_controller.h',
       'cancel_mode.cc',
       'cancel_mode.h',
@@ skipping 1317 matching lines @@
                   '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
                 ],
               }
             ],
           ],
         },
       ],
     }],
   ],
 }