[OBSOLETE] Enable the official AMP plugin to send Server-Timing response headers when WP_DEBUG is enabled or an administrator is logged-in

amp-server-timing.php

<?php
/**
 * Plugin Name: AMP Server-Timing
 * Description: As of <a href="https://wordpress.org/plugins/amp/">AMP plugin</a> v1.2, the <code>Server-Timing</code> response headers are <a href="https://github.com/ampproject/amp-wp/pull/2268">disabled by default</a>. This plugin enables them when <code>WP_DEBUG</code> is enabled or an administrator is logged-in.
 * Plugin URI: https://gist.github.com/westonruter/053f8f47c21df51f1a081fc41b47f547
 * Author: Weston Ruter
 * Author URI: https://weston.ruter.net
 * Version: 1.0
 * License: GPLv2 or later
 * Gist Plugin URI: https://gist.github.com/westonruter/053f8f47c21df51f1a081fc41b47f547
 *
 * @package AMP
 */

add_action(
	'amp_init',
	function () {
		if ( ! class_exists( 'AMP_HTTP' ) || ! property_exists( 'AMP_HTTP', 'server_timing' ) ) {
			return;
		}
		AMP_HTTP::$server_timing = (
			( defined( 'WP_DEBUG' ) && WP_DEBUG )
			||
			current_user_can( 'manage_options' )
		);
	}
);

Installation instructions: https://gist.github.com/westonruter/6110fbc4bef0c4b8c021a112012f7e9c

This is obsolete. Server timings are now sent with all responses. When the user is not logged-in, the are limited to these 4:

If an administrator user is logged-in and the request is made with the ?amp_verbose_server_timing=1 query parameter, then all server timings are sent: