Loads the auth check for monitoring whether the user is still logged in.

Can be disabled with remove_action( ‘admin_enqueue_scripts’, ‘wp_auth_check_load’ );

This is disabled for certain screens where a login screen could cause an
inconvenient interruption. A filter called {@see ‘wp_auth_check_load’} can be used
for fine-grained control.

function wp_auth_check_load() {
	if ( ! is_admin() && ! is_user_logged_in() ) {
		return;
	}

	if ( defined( 'IFRAME_REQUEST' ) ) {
		return;
	}

	$screen = get_current_screen();
	$hidden = array( 'update', 'update-network', 'update-core', 'update-core-network', 'upgrade', 'upgrade-network', 'network' );
	$show   = ! in_array( $screen->id, $hidden, true );

	/**
	 * Filters whether to load the authentication check.
	 *
	 * Returning a falsey value from the filter will effectively short-circuit
	 * loading the authentication check.
	 *
	 * @since 3.6.0
	 *
	 * @param bool      $show   Whether to load the authentication check.
	 * @param WP_Screen $screen The current screen object.
	 */
	if ( apply_filters( 'wp_auth_check_load', $show, $screen ) ) {
		wp_enqueue_style( 'wp-auth-check' );
		wp_enqueue_script( 'wp-auth-check' );

		add_action( 'admin_print_footer_scripts', 'wp_auth_check_html', 5 );
		add_action( 'wp_print_footer_scripts', 'wp_auth_check_html', 5 );
	}
}