Update ProcessorClone test to re-verify problems without using clone().

Previously, this test would synthesize a random FP, call clone(), render
both, and the compare the results and report differences.

Now, if a difference is discovered, this test will re-synthesize the
originally-created random FP from scratch without using clone().
Instead, we call TestCreate again using the same random seed.
Then we can render and compare that output against the original as well.
This will allow to better differentiate failures that were actually
caused by clone(), versus failures caused by other types of

If the regenerated version still mismatches, there are a variety of
potential explanations:
- the FP's TestCreate() does not always generate the same FP from a
  given seed
- the FP's Make() does not always generate the same FP when given the
  same inputs
- the FP itself generates inconsistent pixels (shader UB?)
- the driver has a bug

Change-Id: I71701c0f3d33a08f6ee926313782620487d336bd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/309076
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed