Adds MetalWindowContext_ios and hooks it up to Window_ios.
Also includes some minor clean up in other iOS code.
Bug: skia:8737
Change-Id: I2e8a0c755310fbc4ed534f975815c60f8eca130b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/238438
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
This replaces the SDL-based system and should allow Metal to work on iOS.
OpenGL and raster will render but there's no touch input yet.
Bug: skia:8737
Change-Id: I863accc47f0e1781192d567dbe54d1e321c3cd2e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/231561
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>