Skeleton for app_list on OSX, and refactoring for enable_app_list=1 on OS=="mac".

ui/app_list/app_list.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': [
     {
       'target_name': 'app_list',
       'type': '<(component)',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '../../skia/skia.gyp:skia',
         '../compositor/compositor.gyp:compositor',
         '../ui.gyp:ui',
-        '../views/views.gyp:views',
       ],
       'defines': [
         'APP_LIST_IMPLEMENTATION',
       ],
       'sources': [
-        'app_list_background.cc',
-        'app_list_background.h',
         'app_list_constants.cc',
         'app_list_constants.h',
         'app_list_export.h',
         'app_list_item_model.cc',
         'app_list_item_model.h',
         'app_list_item_model_observer.h',
-        'app_list_item_view.cc',
-        'app_list_item_view.h',
         'app_list_model.cc',
         'app_list_model.h',
         'app_list_model_observer.h',
         'app_list_switches.cc',
         'app_list_switches.h',
-        'app_list_view.cc',
-        'app_list_view.h',
         'app_list_view_delegate.h',
-        'apps_grid_view.cc',
-        'apps_grid_view.h',
         'apps_grid_view_delegate.h',
-        'contents_view.cc',
-        'contents_view.h',
-        'page_switcher.cc',
-        'page_switcher.h',
+        'cocoa/app_list_view_window.h',
+        'cocoa/app_list_view_window.mm',
         'pagination_model.cc',
         'pagination_model.h',
         'pagination_model_observer.h',
-        'pulsing_block_view.cc',
-        'pulsing_block_view.h',
+        'search_box_model.cc',
         'search_box_model.h',
-        'search_box_model.cc',
         'search_box_model_observer.h',
-        'search_box_view.cc',
-        'search_box_view.h',
         'search_box_view_delegate.h',
         'search_result.cc',
         'search_result.h',
-        'search_result_view.cc',
-        'search_result_view.h',
-        'search_result_list_view.cc',
-        'search_result_list_view.h',
         'search_result_list_view_delegate.h',
+        'search_result_view_delegate.h',
+        'views/app_list_background.cc',
+        'views/app_list_background.h',
+        'views/app_list_item_view.cc',
+        'views/app_list_item_view.h',
+        'views/app_list_view.cc',
+        'views/app_list_view.h',
+        'views/apps_grid_view.cc',
+        'views/apps_grid_view.h',
+        'views/contents_view.cc',
+        'views/contents_view.h',
+        'views/page_switcher.cc',
+        'views/page_switcher.h',
+        'views/pulsing_block_view.cc',
+        'views/pulsing_block_view.h',
+        'views/search_box_view.cc',
+        'views/search_box_view.h',
+        'views/search_result_list_view.cc',
+        'views/search_result_list_view.h',
+        'views/search_result_view.cc',
+        'views/search_result_view.h',
       ],
       'conditions': [
         ['use_aura==1', {
           'dependencies': [
             '../aura/aura.gyp:aura',
           ],
         }],
+        ['toolkit_views==1', {
+          'dependencies': [
+            '../views/views.gyp:views',
+          ],
+        }, {  # toolkit_views==0
+          'sources/': [
+            ['exclude', 'views/'],
+          ],
+        }],
+        ['OS!="mac"', {
+          'sources/': [
+            ['exclude', 'cocoa/'],
+          ],
+        }],
       ],
     },
     {
       'target_name': 'app_list_unittests',
       'type': 'executable',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/base.gyp:test_support_base',
         '../../skia/skia.gyp:skia',
         '../../testing/gtest.gyp:gtest',
         '../compositor/compositor.gyp:compositor',
         '../compositor/compositor.gyp:compositor_test_support',
-        '../views/views.gyp:views',
-        '../views/views.gyp:views_test_support',
         'app_list',
       ],
       'sources': [
-        'apps_grid_view_unittest.cc',
         'pagination_model_unittest.cc',
-        'test/apps_grid_view_test_api.cc',
-        'test/apps_grid_view_test_api.h',
         'test/app_list_test_suite.cc',
         'test/app_list_test_suite.h',
         'test/run_all_unittests.cc',
+        'cocoa/app_list_view_window_unittest.mm',
+        'views/apps_grid_view_unittest.cc',
+        'views/test/apps_grid_view_test_api.cc',
+        'views/test/apps_grid_view_test_api.h',
+      ],
+      'conditions': [
+        ['toolkit_views==1', {
+          'dependencies': [
+            '../views/views.gyp:views',
+            '../views/views.gyp:views_test_support',
+          ],
+        }, {  # toolkit_views==0
+          'sources/': [
+            ['exclude', 'views/'],
+          ]
+        }],
+        ['OS=="mac"', {
+          'dependencies': [
+            '../ui.gyp:ui_test_support',
+          ],
+        }, {  # OS!="mac"
+          'sources/': [
+            ['exclude', 'cocoa/'],
+          ],
+        }],
       ],
     },
   ],
 }