/**
  * Check protected/allowed extension
  *
  * @param string $extension
  * @return boolean
  */
 public function checkAllowedExtension($extension)
 {
     //validate with protected file types
     /** @var $validator Mage_Core_Model_File_Validator_NotProtectedExtension */
     $validator = Mage::getSingleton('core/file_validator_notProtectedExtension');
     if (!$validator->isValid($extension)) {
         return false;
     }
     return parent::checkAllowedExtension($extension);
 }