Make it possible to build without enable_supervised_users.

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index 99331b1156d28ffc28067f0eb67c8b6e65cfa993..735dcbb8c67322aeb5822464380d34e56bef3f21 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -2995,7 +2995,6 @@ test("unit_tests") {
     "../browser/component_updater/origin_trials_component_installer_unittest.cc",
     "../browser/component_updater/sth_set_component_installer_unittest.cc",
     "../browser/component_updater/subresource_filter_component_installer_unittest.cc",
-    "../browser/component_updater/supervised_user_whitelist_installer_unittest.cc",
     "../browser/component_updater/sw_reporter_installer_win_unittest.cc",
     "../browser/conflicts/installed_programs_win_unittest.cc",
     "../browser/conflicts/module_database_win_unittest.cc",
@@ -4803,6 +4802,7 @@ test("unit_tests") {
   }
   if (enable_supervised_users) {
     sources += [
+      "../browser/component_updater/supervised_user_whitelist_installer_unittest.cc",
       "../browser/content_settings/content_settings_supervised_provider_unittest.cc",
       "../browser/supervised_user/child_accounts/family_info_fetcher_unittest.cc",
       "../browser/supervised_user/child_accounts/permission_request_creator_apiary_unittest.cc",