collapse some unused type hierarchy

SkBitmapProcState is the only subclass of SkBitmapProcInfo, and
BitmapProcShaderContext the only subclass of BitmapProcInfoContext.

This folds it all together, and should be a no-op refactor.

Change-Id: I971c03dbbebfcd1651ddac2f1b624329f415cc35
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/313439
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>
3 files changed