Add an experiment for the default browser infobar on Windows 10

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': [
       # histograms.xml is analyzed by AboutFlagsHistogramTest, so this
       # dependency is needed to make commit bots run unit_tests on
       # histograms.xml changes.
       '../tools/metrics/histograms/histograms.xml',
@@ skipping 259 matching lines @@
       'browser/ui/bookmarks/bookmark_ui_utils_desktop_unittest.cc',
       'browser/ui/bookmarks/recently_used_folders_combo_model_unittest.cc',
       'browser/ui/chrome_select_file_policy_unittest.cc',
       'browser/ui/find_bar/find_backend_unittest.cc',
       'browser/ui/login/login_handler_unittest.cc',
       'browser/ui/passwords/manage_passwords_state_unittest.cc',
       'browser/ui/passwords/manage_passwords_view_utils_unittest.cc',
       'browser/ui/passwords/password_bubble_experiment_unittest.cc',
       'browser/ui/passwords/password_manager_presenter_unittest.cc',
       'browser/ui/search_engines/keyword_editor_controller_unittest.cc',
+      'browser/ui/startup/default_browser_infobar_delegate_unittest.cc',
       'browser/ui/sync/profile_signin_confirmation_helper_unittest.cc',
       'browser/ui/sync/sync_promo_ui_unittest.cc',
       'browser/ui/tests/ui_gfx_image_unittest.cc',
       'browser/ui/tests/ui_gfx_image_unittest.mm',
       'browser/ui/website_settings/website_settings_unittest.cc',
       'browser/ui/webui/browsing_history_handler_unittest.cc',
       'browser/ui/webui/fileicon_source_unittest.cc',
       'browser/ui/webui/local_state/local_state_ui_unittest.cc',
       'browser/ui/webui/log_web_ui_url_unittest.cc',
       'browser/update_client/chrome_update_query_params_delegate_unittest.cc',
@@ skipping 2706 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }