[WIP] ash/extensions: Add experimental extension support for window-management in ash.

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,
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
   },
 
@@ skipping 302 matching lines @@
         'wm/visibility_controller.cc',
         'wm/visibility_controller.h',
         'wm/window_animations.cc',
         'wm/window_animations.h',
         'wm/window_cycle_controller.cc',
         'wm/window_cycle_controller.h',
         'wm/window_cycle_list.cc',
         'wm/window_cycle_list.h',
         'wm/window_frame.cc',
         'wm/window_frame.h',
+        'wm/window_manager_extension.cc',
+        'wm/window_manager_extension.h',
         'wm/window_modality_controller.cc',
         'wm/window_modality_controller.h',
         'wm/window_properties.cc',
         'wm/window_properties.h',
         'wm/window_resizer.cc',
         'wm/window_resizer.h',
         'wm/window_util.cc',
         'wm/window_util.h',
         'wm/workspace_controller.cc',
         'wm/workspace_controller.h',
@@ skipping 271 matching lines @@
             'shell/cocoa/app-Info.plist',
           ],
           'xcode_settings': {
             'INFOPLIST_FILE': 'shell/cocoa/app-Info.plist',
           },
         }],
       ],
     },
   ],
 }