Motivation: make is easier to add multiple views sharing a GrContext.
- Split configure_mtk_view() from to_context()
- AppViewDelegate no longer owns GrContext
- Split out config_paint() and draw_example() fns
to delineate example code from useful code.
- AppViewDelegate no longer responsible for initializing
itself.
- AppViewController owns MTLDevice and GrContext.
No-Try: true
Change-Id: I608da76c7818b262c0bfbe52dd431f3007e86e2d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/240201
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
56df7910b0