Make win_aura work without ash.

ui/aura/aura.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,
   },
   'targets': [
     {
@@ skipping 39 matching lines @@
         'client/visibility_client.h',
         'client/window_move_client.cc',
         'client/window_move_client.h',
         'client/window_types.h',
         'desktop/desktop_activation_client.cc',
         'desktop/desktop_activation_client.h',
         'desktop/desktop_dispatcher_client.cc',
         'desktop/desktop_dispatcher_client.h',
         'desktop/desktop_root_window_event_filter.cc',
         'desktop/desktop_root_window_event_filter.h',
+        'desktop/desktop_screen.h',
+        'desktop/desktop_screen_win.cc',
+        'desktop/desktop_screen_win.h',
+        'desktop/desktop_screen_x11.cc',
         'desktop/desktop_stacking_client.cc',
         'desktop/desktop_stacking_client.h',
         'dispatcher_linux.cc',
         'dispatcher_linux.h',
         'dispatcher_win.cc',
         'env.cc',
         'env.h',
         'env_observer.h',
         'event.cc',
         'event.h',
@@ skipping 142 matching lines @@
         # osmesa GL implementation is used on linux.
         ['OS=="linux"', {
           'dependencies': [
             '<(DEPTH)/third_party/mesa/mesa.gyp:osmesa',
           ],
         }],
       ],
     },
   ],
 }