These are much safer than SkReader32/SkWriter32 (they do validation and
ensure we never read past the end of the buffer).
Where we used to just assert that the contents of the cache were valid,
we now validate everything, and fail gracefully by discarding the cache
contents if it's corrupted or invalid.
Bug: skia:9402
Change-Id: Ib893681f97f9413c28744f11075dc2e392364db6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/294998
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
5fa11d4040