Source

File: wp-admin/includes/class-wp-upgrader-skin.php

public function request_filesystem_credentials( $error = false, $context = '', $allow_relaxed_file_ownership = false ) {
		$url = $this->options['url'];
		if ( ! $context ) {
			$context = $this->options['context'];
		}
		if ( ! empty( $this->options['nonce'] ) ) {
			$url = wp_nonce_url( $url, $this->options['nonce'] );
		}

		$extra_fields = array();

		return request_filesystem_credentials( $url, '', $error, $context, $extra_fields, $allow_relaxed_file_ownership );
	}