/**
 * Take the provided URL and make sure it can be parsed, it's of the
 * expected origin, and has the specified locale.
 *
 * If it can't be parsed or if it's not of the expected origin, return null.
 * Setting URL to null will display an error message in the iframe
 *
 * @param urlString - The URL to make safe.
 * @param locale - The locale to use for the URL.
 * @param expectedOrigin - The expected origin of the URL.
 * @returns The safe URL, or null if the URL is not safe.
 */
export declare const makeSafeUrl: (urlString: string, locale: string, expectedOrigin: string) => URL | null;