Code review comment for lp:~kdub/mir/demo-stream-titlebars

> I don't see where this is being used.
> 640 + SurfaceCreationParameters&
> with_buffer_streams(std::vector<shell::StreamSpecification> const& streams);
>
> why is it needed? Is there a followup branch?

It is providing a similar way to set the stream fields, eg:
ms::a_surface()
    .with_size(...)
    .with_bufer_usage(...)
    .with_buffer_streams(...);