Add a mechanism to force parameters of a group to a specific value.

chrome/chrome_tests_unit.gypi

 # Copyright 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': {
     'chrome_unit_tests_sources': [
       '../components/autofill/content/renderer/test_password_autofill_agent.cc',
       '../components/autofill/content/renderer/test_password_autofill_agent.h',
       '../components/autofill/content/renderer/test_password_generation_agent.cc',
       '../components/autofill/content/renderer/test_password_generation_agent.h',
@@ skipping 546 matching lines @@
       'common/mac/cfbundle_blocker_unittest.mm',
       'common/mac/mock_launchd.cc',
       'common/mac/mock_launchd.h',
       'common/mac/objc_zombie_unittest.mm',
       'common/origin_util_unittest.cc',
       'common/partial_circular_buffer_unittest.cc',
       'common/pref_names_util_unittest.cc',
       'common/search_urls_unittest.cc',
       'common/switch_utils_unittest.cc',
       'common/variations/experiment_labels_unittest.cc',
+      'common/variations/variations_util_unittest.cc',
       'common/worker_thread_ticker_unittest.cc',
       'renderer/chrome_content_renderer_client_unittest.cc',
       'renderer/content_settings_observer_unittest.cc',
       'renderer/instant_restricted_id_cache_unittest.cc',
       'renderer/plugins/plugin_uma_unittest.cc',
       'renderer/prerender/prerender_dispatcher_unittest.cc',
       'renderer/resources/extensions/notifications_custom_bindings.js',
       'renderer/resources/extensions/notifications_custom_bindings.gtestjs',
       'renderer/resources/extensions/notifications_test_util.js',
       'renderer/searchbox/search_bouncer_unittest.cc',
@@ skipping 2199 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }