Add policy provider that would filter extensions/apps allowed on the

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 965 matching lines @@
       'browser/chromeos/drive/write_on_cache_file_unittest.cc',
       'browser/chromeos/events/event_rewriter_unittest.cc',
       'browser/chromeos/events/keyboard_driven_event_rewriter_unittest.cc',
       'browser/chromeos/extensions/default_app_order_unittest.cc',
       'browser/chromeos/extensions/device_local_account_external_policy_loader_unittest.cc',
       'browser/chromeos/extensions/device_local_account_management_policy_provider_unittest.cc',
       'browser/chromeos/extensions/external_cache_unittest.cc',
       'browser/chromeos/extensions/file_manager/device_event_router_unittest.cc',
       'browser/chromeos/extensions/file_manager/job_event_router_unittest.cc',
       'browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api_unittest.cc',
+      'browser/chromeos/extensions/signin_screen_policy_provider_unittest.cc',
       'browser/chromeos/extensions/wallpaper_private_api_unittest.cc',
       'browser/chromeos/external_metrics_unittest.cc',
       'browser/chromeos/file_manager/file_tasks_unittest.cc',
       'browser/chromeos/file_manager/file_watcher_unittest.cc',
       'browser/chromeos/file_manager/fileapi_util_unittest.cc',
       'browser/chromeos/file_manager/mount_test_util.cc',
       'browser/chromeos/file_manager/path_util_unittest.cc',
       'browser/chromeos/file_manager/url_util_unittest.cc',
       'browser/chromeos/file_manager/volume_manager_unittest.cc',
       'browser/chromeos/file_system_provider/fake_provided_file_system.cc',
@@ skipping 2029 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }