simplify cached bitmap in table CF

Don't create the bitmap in a lazy, thread-unsafe way.
Create it in a proactive, thread-safe way.

There's still opportunity to dedup the data between
fStorage and fBitmap that I'll follow up on next.

Change-Id: I1a71fbc560c84ff1e9e6b8c05673e461417a5b58
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/376598
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed