Suppress flaky test on macos for CrSettingsMainPageTest.MainPage

chrome/test/data/webui/settings/cr_settings_browsertest.js

 // Copyright 2015 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.
 
 /** @fileoverview Runs the Polymer Settings tests. */
 
 /** @const {string} Path to source root. */
 var ROOT_PATH = '../../../../../';
 
 // Polymer BrowserTest fixture.
@@ skipping 919 matching lines @@
         done();
       });
       window.history.back();
     });
   });
   mocha.run();
 });
 
 // Times out on Windows Tests (dbg). See https://crbug.com/651296.
 // Times out / crashes on chromium.linux/Linux Tests (dbg) crbug.com/667882
-GEN('#if defined(OS_WIN) || defined(OS_CHROMEOS) || defined(OS_LINUX)');
+GEN('#if defined(OS_WIN) || defined(OS_CHROMEOS) || defined(OS_LINUX)' +
+    ' || defined(OS_MACOSX)');
 GEN('#define MAYBE_MainPage_All DISABLED_All');
 GEN('#else');
 GEN('#define MAYBE_MainPage_All All');
 GEN('#endif');
 
 /**
  * Test fixture for chrome/browser/resources/settings/settings_main/.
  * @constructor
  * @extends {CrSettingsBrowserTest}
  */
@@ skipping 208 matching lines @@
   extraLibraries: CrSettingsBrowserTest.prototype.extraLibraries.concat([
     'test_browser_proxy.js',
     'test_extension_control_browser_proxy.js',
     'extension_controlled_indicator_tests.js',
   ]),
 };
 
 TEST_F('CrSettingsExtensionControlledIndicatorTest', 'All', function() {
   mocha.run();
 });