Rename *worstCase* to backingStore* in GrSurfaceProxy

These names are more appropriate after:

https://skia-review.googlesource.com/c/skia/+/241356 (Always create an approx-size texture for approx-fit proxies))

Note that this CL does have one substantive change in GrCoordTransform::hasSameEffectAs where we use our knowledge of the size at which the backing stores will be allocated to remove a sly usage of GrSurfaceProxy::underlyingUniqueID.

Change-Id: Ibbb8cb23c4503f267abbdf4794610f3262a6f515
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/250257
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
9 files changed