protected function install_plugin() {

		include_once ABSPATH . 'wp-admin/includes/plugin-install.php';
		include_once ABSPATH . 'wp-admin/includes/file.php';
		include_once ABSPATH . 'wp-admin/includes/class-wp-upgrader.php';

		// Use the WordPress Plugins API to get the plugin download link.
		$api = plugins_api(
			'plugin_information',
			array(
				'slug' => $this->id,
			)
		);
		if ( is_wp_error( $api ) ) {
			return $api;
		}

		// Use the AJAX upgrader skin to quietly install the plugin.
		$upgrader = new Plugin_Upgrader( new WP_Ajax_Upgrader_Skin() );
		$install  = $upgrader->install( $api->download_link );
		if ( is_wp_error( $install ) ) {
			return $install;
		}

		$activate = activate_plugin( $upgrader->plugin_info() );
		if ( is_wp_error( $activate ) ) {
			return $activate;
		}

		return true;

	}