Makes workspace 2 show an alternate background (system background)

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 326 matching lines @@
         'wm/workspace/managed_workspace.h',
         'wm/workspace/maximized_workspace.cc',
         'wm/workspace/maximized_workspace.h',
         'wm/workspace/multi_window_resize_controller.cc',
         'wm/workspace/multi_window_resize_controller.h',
         'wm/workspace/phantom_window_controller.cc',
         'wm/workspace/phantom_window_controller.h',
         'wm/workspace/snap_sizer.cc',
         'wm/workspace/snap_sizer.h',
         'wm/workspace/snap_types.h',
+        'wm/workspace/system_background_controller.cc',
+        'wm/workspace/system_background_controller.h',
         'wm/workspace/workspace.cc',
         'wm/workspace/workspace.h',
         'wm/workspace/workspace2.cc',
         'wm/workspace/workspace2.h',
         'wm/workspace/workspace_event_filter.cc',
         'wm/workspace/workspace_event_filter.h',
         'wm/workspace/workspace_layout_manager.cc',
         'wm/workspace/workspace_layout_manager.h',
         'wm/workspace/workspace_layout_manager2.cc',
         'wm/workspace/workspace_layout_manager2.h',
@@ skipping 254 matching lines @@
             'shell/cocoa/app-Info.plist',
           ],
           'xcode_settings': {
             'INFOPLIST_FILE': 'shell/cocoa/app-Info.plist',
           },
         }],
       ],
     },
   ],
 }