Controller間共通でHTTPヘッダを追加する方法 ref: http://qiita.com/uchiko/items/e61d11ddff71e5330194

public.php

class Controller_Public extends Controller_Template
{
    pubulic function after($response)
    {
        $response = parent::after($response);
        $response->set_header('X-FRAME-OPTIONS', 'SAMEORIGIN');
        return $response;
    }
}