Code review comment for lp:~kdub/mir/split-platform-into-rendering-and-display

> I am not sure how these two can be completely independent. E.g. buffer
> allocator is on the renderer side, but for overlays e.g., the allocator needs
> to know things about display. Perhaps there will need to be a common base
> class or an interface between the two. Can't see that far into the future. I
> guess, we can start here and add things as needed.

mesa-kms and android will construct their own buffers without needing the one from the system (android at least uses allocations not available to the system anyways). If its the right thing to do at some pointin the future, no objection from me from having the Rendering use the Display platform (or vice-versa).