WordPress - Add new page in dashboard (iframe Google)

functions.php

<?php
add_action('admin_menu','add_new_page');
function add_new_page(){
    function add_new_page_content(){
        include('inc-admin-new-page.php');
    }
    add_menu_page('New Page', 'New Page', 'publish_posts', 'new-page','add_new_page_content','');
}

// Google Presentation
/*
add_action('wp_dashboard_setup', 'add_dashboard_widgets' );
function add_dashboard_widgets() {
    wp_add_dashboard_widget('dashboard_widget', 'Tutoriais', function($post, $callback_args){
        echo '<iframe src="https://docs.google.com/presentation/d/1keoR1COIST1HtOI1TcONd0H-WOEsMzAjYmx43xZ8y/embed?start=false&loop=false&delayms=3000" frameborder="0" width="390" height="250" allowfullscreen="true" mozallowfullscreen="true" webkitallowfullscreen="true"></iframe>';
    });
}
*/