Reland "Have GrAtlasManager use legacy behavior"

This is a reland of 4b7b2ceb4ad93861c2ae6b4fabce13f187ec4b93

Original change's description:
> Have GrAtlasManager use legacy behavior
>
> The old code would generate a 1024 x 2048 x 4 atlas given a
> max size of 4MiB. And, the plot sizes would be 256 x 256. This CL
> mimics that behavior.
>
> Change-Id: Iae741d5409daa034c6c3086c8a09476fb343353d
> Reviewed-on: https://skia-review.googlesource.com/c/162321
> Commit-Queue: Herb Derby <herb@google.com>
> Reviewed-by: Mike Klein <mtklein@google.com>

Change-Id: I86cc8d2fb07f5317897f094c6fc172c1ca4c8a1c
Reviewed-on: https://skia-review.googlesource.com/c/162720
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Herb Derby <herb@google.com>
2 files changed