Add support for gray + colorspace to SkCodec

Bug: skia:
Change-Id: Ib0996ac5aff5eeb4bd67e9938ad0d9246703a0e7
Reviewed-on: https://skia-review.googlesource.com/151661
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
14 files changed