Source

File: wp-includes/widgets/class-wp-widget-custom-html.php

public function __construct() {
		$widget_ops  = array(
			'classname'                   => 'widget_custom_html',
			'description'                 => __( 'Arbitrary HTML code.' ),
			'customize_selective_refresh' => true,
		);
		$control_ops = array(
			'width'  => 400,
			'height' => 350,
		);
		parent::__construct( 'custom_html', __( 'Custom HTML' ), $widget_ops, $control_ops );
	}