[WordPress][Cachify] Mini plugin to move Cachify’s trash icon to the primary/left part of the admin bar.

cachify-custom-admin-bar-icon.php

<?php
/**
 * Plugin Name: Cachify | Customize admin bar icon.
 * Description: Moves Cachify’s trash icon to the primary/left part of the admin bar.
 * Version:     2015.12
 * Author:      Caspar Hübinger
 * Author URI:  https://profiles.wordpress.org/glueckpress/
 * Plugin URI:  https://gist.github.com/glueckpress/0ccc84e6f93b89dee1d3
 * License:     GNU General Public License v3
 * License URI: http://www.gnu.org/licenses/gpl-3.0.html
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Initialize plugin.
 *
 * @return void
 */
function cachify_customize_admin_bar_icon() {

	if ( ! class_exists( 'Cachify' ) )
		return;

	// Remove default admin bar icon.
	remove_action( 'admin_bar_menu', array( 'Cachify', 'add_flush_icon' ), 90 );

	// Add custom admin bar icon.
	add_action( 'admin_bar_menu', 'cachify_customize_admin_bar_icon__add_flush_icon', 90 );
}
add_action( 'after_setup_theme', 'cachify_customize_admin_bar_icon' );

/**
 * Modified Cachify Trash Admin Bar Icon.
 *
 * @param  object $wp_admin_bar Admin bar object
 * @return void
 */
function cachify_customize_admin_bar_icon__add_flush_icon( $wp_admin_bar ) {

	if ( ! is_admin_bar_showing() OR ! apply_filters( 'cachify_user_can_flush_cache', current_user_can( 'manage_options' ) ) ) {
		return;
	}

	$wp_admin_bar->add_menu(
		array(
			'id'     => 'cachify',
			'href'   => wp_nonce_url( add_query_arg( '_cachify', 'flush' ), '_cachify__flush_nonce' ),
			'title'  => sprintf(
				'<span class="ab-icon dashicons dashicons-trash"><span class="screen-reader-text">%s</span></span>',
				__( 'Flush the cachify cache', 'cachify' )
			),
			'meta'   => array(
				'title' => esc_attr__( 'Flush the cachify cache', 'cachify' )
			)
		)
	);
}