Restricting users to view only media library items they have uploaded

<?php
function users_own_attachments( $wp_query_obj ) {
    global $current_user, $pagenow;
    $is_attachment_request = ($wp_query_obj->get('post_type')=='attachment');
    if( !$is_attachment_request )
        return;
    if( !is_a( $current_user, 'WP_User') )
        return;
    if( !in_array( $pagenow, array( 'upload.php', 'admin-ajax.php' ) ) )
        return;
    if( !current_user_can('delete_pages') )
        $wp_query_obj->set('author', $current_user->ID );
    return;
}
add_action('pre_get_posts','users_own_attachments');