WordPress管理画面の投稿一覧にスラッグを追加する（固定ページも）

/* 投稿一覧にスラッグ追加 */
function add_posts_columns_slug($columns) { 
    $columns['slug'] = 'スラッグ'; 
    return $columns; 
} 
function add_posts_columns_slug_row($column_name, $post_id) { 
    if( $column_name == 'slug' ) { 
        $slug = get_post($post_id) -> post_name; 
        echo esc_attr($slug); 
    } 
} 
add_filter( 'manage_posts_columns', 'add_posts_columns_slug' ); 
add_action( 'manage_posts_custom_column', 'add_posts_columns_slug_row', 10, 2 );

/* 固定ページ一覧にスラッグ追加 */
function add_page_columns_slug($columns) { 
    $columns['slug'] = 'スラッグ'; 
    return $columns; 
} 
function add_page_column_slug_row($column_name, $post_id) { 
    if( $column_name == 'slug' ) { 
        $slug = get_post($post_id) -> post_name; 
        echo esc_attr($slug); 
    } 
} 
add_filter( 'manage_pages_columns', 'add_page_columns_slug'); 
add_action( 'manage_pages_custom_column', 'add_page_column_slug_row', 10, 2);