Code review comment for lp:~alan-griffiths/mir/discussion-migrate-demo-shell

Our downstreams have been able to get along without our utility classes (
gl_program, gl_texture, gl_primitive, gl_renderer, etc) to this point, and re-exposing them exposes a lot of ABI that has been hidden and is not used. These classes are more utility classes of the way we've used GLES internally than a recommendation/suggestion to others as to how they should use GLES.

I think its possible to transition the demo shell from playground to examples with a bit of more in-depth "surgery" to have it target reimplementing our already-exposed /interfaces/ instead of overriding different components of utility classes.