cleanup SkColorSpace API and members

I think this is the cleanup we can do immediately
once I rebaseline the previous CL.

Nothing will be using fromXYZD50() any longer.

I've made toXYZD50() lazily cache its SkMatrix44.
Not to many people call that function, so it'd be a
pretty straightforward cleanup to switch to the one
that writes to an SkMatrix44*, which is just fine.

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Iad45ef7c95ed7f9a9528d543f2307490ca5de087
Reviewed-on: https://skia-review.googlesource.com/158000
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed