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

> Looks reasonable to me, modulo Alan's needs-fixing.
>
> This isn't code for actual Mir shell clients to use, and we don't need to
> implement fancy decorations in our demo server.

Right, this is just to stop giving an example of binding up a MirSurface to use as a titlebar, and to eliminate a use of the 'primary_buffer_stream()'