WordPress - Debug Bar Panel class

custom-debug-bar-panel-class.php

<?php

Class CustomDebugBarPanel extends Debug_Bar_Panel {
	public function init() {
		$this->title(__('Custom Debug Bar Panel', 'debug-bar'));
		add_action('wp_print_styles', array( $this, 'print_styles'));
		add_action('admin_print_styles', array( $this, 'print_styles'));
	}

	public function prerender() {
		$this->set_visible(true);
	}

	public function print_styles() {
		wp_enqueue_style('custom-debug-bar-panel', plugins_url('css/custom-debug-bar-panel.css', __FILE__));
	}

	public function render() {
		?>
			<div class="debug-bar-cron">
				<p>Content goes here</p>
			</div>
		<?php
	}
}

plugin.php

<?php

/* Plugin name: Custom Debug Bar Panel */

add_filter('debug_bar_panels', function($panels) {
  include_once('custom-debug-bar-panel-class.php');
	$panels[] = new CustomDebugBarPanel();
	return $panels;
});