This adds adds four macros when compiling using GTEST_OS_MAC:

chrome/chrome_tests.gypi

 # Copyright (c) 2010 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' : {
     'pyautolib_sources': [
       'app/chrome_dll_resource.h',
       'common/pref_names.cc',
       'common/pref_names.h',
@@ skipping 1215 matching lines @@
         'test/menu_model_test.cc',
         'test/menu_model_test.h',
         'test/render_view_test.cc',
         'test/render_view_test.h',
         'test/sync/test_http_bridge_factory.h',
         'test/test_notification_tracker.cc',
         'test/test_notification_tracker.h',
         'test/v8_unit_test.cc',
         'test/v8_unit_test.h',
         'tools/convert_dict/convert_dict_unittest.cc',
+        '../testing/gtest_mac_unittest.mm',
         '../third_party/cld/encodings/compact_lang_det/compact_lang_det_unittest_small.cc',
         # TODO(jcampan): Create a separate unit test for these to allow us to
         # test views completely decoupled from chrome.
         '../views/animation/bounds_animator_unittest.cc',
         '../views/box_layout_unittest.cc',
         '../views/controls/label_unittest.cc',
         '../views/controls/progress_bar_unittest.cc',
         '../views/controls/tabbed_pane/tabbed_pane_unittest.cc',
         '../views/controls/table/table_view_unittest.cc',
         '../views/focus/accelerator_handler_gtk_unittest.cc',
@@ skipping 1513 matching lines @@
       ]
     }],  # 'coverage!=0'
   ],  # 'conditions'
 }
 
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 # tab-width:2
 # indent-tabs-mode:nil
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