Hide the "downloads" page policy disabled UI elements from supervised users

chrome/chrome_tests.gypi

 # Copyright 2013 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_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 1623 matching lines @@
         'browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc',
         'browser/ui/views/select_file_dialog_extension_browsertest.cc',
         'browser/ui/views/toolbar_view_browsertest.cc',
         'browser/ui/views/web_dialog_view_browsertest.cc',
         'browser/ui/webui/bidi_checker_web_ui_test.cc',
         'browser/ui/webui/bidi_checker_web_ui_test.h',
         'browser/ui/webui/bookmarks_ui_browsertest.cc',
         'browser/ui/webui/chrome_url_data_manager_browsertest.cc',
         'browser/ui/webui/constrained_web_dialog_ui_browsertest.cc',
         'browser/ui/webui/downloads_dom_handler_browsertest.cc',
+        'browser/ui/webui/downloads_ui_browsertest.cc',
+        'browser/ui/webui/downloads_ui_browsertest.h',
+        'browser/ui/webui/downloads_ui_browsertest.js',
         'browser/ui/webui/extensions/chromeos/kiosk_apps_browsertest.js',
         'browser/ui/webui/extensions/extension_settings_browsertest.js',
         'browser/ui/webui/help/help_browsertest.js',
         'browser/ui/webui/identity_internals_ui_browsertest.cc',
         'browser/ui/webui/identity_internals_ui_browsertest.h',
         'browser/ui/webui/identity_internals_ui_browsertest.js',
         'browser/ui/webui/inspect_ui_browsertest.cc',
         'browser/ui/webui/net_internals/net_internals_ui_browsertest.cc',
         'browser/ui/webui/net_internals/net_internals_ui_browsertest.h',
         'browser/ui/webui/ntp/most_visited_browsertest.cc',
@@ skipping 1819 matching lines @@
             'utility',
           ],
           'sources': [
             'tools/service_discovery_sniffer/service_discovery_sniffer.h',
             'tools/service_discovery_sniffer/service_discovery_sniffer.cc',
           ],
         }]
     }],
   ],  # 'conditions'
 }