This moves getting and setting the value of app.update.auto from nsUpdateService.js to UpdateUtils.jsm so nsUpdateService.js isn't loaded during startup Changes the browser_policy_app_update_URL.js test to check the default pref for app.update.url since the default pref is read by app update Fixes a NS_NOINTERFACE error in app update xpcshell tests for AppInfo not implementing nsIPlatformInfo Differential Revision: https://phabricator.services.mozilla.com/D13285