Code review comment for lp:~afrantzis/mir/expose-display-buffer-only-for-power-mode-on

> > might be pre-existing, but I think android needs some locking around the
> power_mode configuring and skipping the DisplayBuffer.
>
> The problem is that we will be calling a callback with a lock held. We are
> doing the same in mesa/display.cpp though, so we might as well make the two
> backends equally susceptible to deadlock. Of course we could try to fix them
> both somehow, but I don't see any reasonable solution other than creating
> copies of the DisplayBuffers, which has its own set of problems.

okay, looks good to me