[Athena] minimum impl to add screen/background and test windows

athena/main/athena_main.gyp

 # Copyright 2014 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': [
     {
       'target_name': 'athena_main',
       'type': 'executable',
       'dependencies': [
+        '../athena.gyp:athena_lib',
         '../../apps/shell/app_shell.gyp:app_shell_lib',
+        '../../skia/skia.gyp:skia',
+        '../../ui/accessibility/accessibility.gyp:ax_gen',
+        '../../ui/views/views.gyp:views',
       ],
       'include_dirs': [
         '../..',
       ],
       'sources': [
         'athena_main.cc',
+        'placeholder.cc',
+        'placeholder.h',
       ],
     },
   ],  # targets
 }