Change code to not store Sk4* in data structures.

This allows the SkLinearBitmapPipeline system to avoid problems with alignment. This allows it to naturally fit with the rest of the system, and simplifies surrounding code.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2486523002

Review-Url: https://codereview.chromium.org/2486523002
5 files changed