get current menu item classes from page ID

menu-item-classes-from-page-id.php

<?php
add_filter( 'nav_menu_css_class' , 'get_nav_classes' , 10 , 2 );
function get_nav_classes( $classes, $item ) {
	global $post;
        if ( 'page' != get_post_type() ) {
            return $classes;
        }

	$link_page_id = get_post_meta( $item->ID, '_menu_item_object_id', true ); 
	if ( $post->ID == $link_page_id ) {
		// Gotcha!
	}
     }
     return $classes;
}
?>