Merge GrContext::init into GrDirectContext ...

And minor cleanups associated with the initialization of these classes.

Change-Id: Ida0372d0b1a0b8bf5b309814de5418e47ea34fdb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324122
Commit-Queue: Adlai Holler <adlai@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Auto-Submit: Adlai Holler <adlai@google.com>
5 files changed