base_delivery_carrier_label evolution

Here is common method I would like add to base_delivery_carrier_label, to have a common api

class StockQuantPackage(models.Model):
    _inherit = 'stock.quant.package'

    carrier_id = field.Many2one('delivery.carrier')

    @api.multi
    def _get_carrier_tracking_url(self):
        """ In your own module:
            res = super(StockQuantPackage, self)._get_carrier_tracking_url()
            if self.carrier_id.type == 'my_carrier':
                res = "http://my_carrier/%s" % self.parcel_tracking
            return res 
        """
        raise UserError(_("No carrier tracking url for this package"))

    # button in the interface
    @api.multi
    def open_tracking_url(self):
        self.ensure_one()
        if not self.parcel_tracking:
            raise UserError(
                _("Cannot open tracking URL for this carrier "
                  "because this package "
                  "doesn't have a tracking number."))
        return {
            'type': 'ir.actions.act_url',
            'url': self._get_carrier_tracking_url(),
            'target': 'new',
        }

class StockPackOperation(models.Model):
    _inherit = 'stock.pack.operation'

    # button in the interface
    @api.multi
    def open_tracking_url(self):
        self.ensure_one()
        if self.result_package_id and self.result_package_id.parcel_tracking:
            self.result_package_id.open_tracking_url()


class StockPicking(models.Model):
    _inherit = "stock.picking"

    carrier_tracking_ref = fields.Char(copy=False)