def default_batch_size(self):
        """Returns the default batch size to use for this port."""
        if self.get_option('enable_sanitizer'):
            # ASAN/MSAN/TSAN use more memory than regular content_shell. Their
            # memory usage may also grow over time, up to a certain point.
            # Relaunching the driver periodically helps keep it under control.
            return 40
        # The default is infinite batch size.
        return 0