Alpha type is not (and never will be) part of pixel config, so the logic
around that was unnecessary. (Also, we already sanitize color type and
alpha type before making a new device at a higher level).
With that out of the way, we can easily supply a full info at the two
call-sites that were using the other version.
BUG=skia:
Change-Id: Iceccdbdebd1062d3e5023620755aabcc86604d2f
Reviewed-on: https://skia-review.googlesource.com/6920
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
0c2997b6d8