athena: Add a minimal executable for just the UI.

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': [
     {
@@ skipping 10 matching lines @@
         '../..',
       ],
       'sources': [
         'athena_launcher.cc',
         'athena_launcher.h',
         'athena_main.cc',
         'placeholder.cc',
         'placeholder.h',
       ],
     },
+    {
+      'target_name': 'athena_shell',
+      'type': 'executable',
+      'dependencies': [
+        '../../base/base.gyp:base',
+        '../../base/base.gyp:base_i18n',
+        '../../skia/skia.gyp:skia',
+        '../../ui/accessibility/accessibility.gyp:ax_gen',
+        '../../ui/aura/aura.gyp:aura',
+        '../../ui/compositor/compositor.gyp:compositor_test_support',
+        '../../ui/gfx/gfx.gyp:gfx',
+        '../athena.gyp:athena_lib',
+        '../athena.gyp:athena_test_support',
+      ],
+      'sources': [
+        'athena_shell.cc',
+      ],
+    }
   ],  # targets
 }