Add unit tests for vertexData in the thread-safe cache

Bug: 1108408
Change-Id: Ia984324d559bb33bfe668a44ee93c6e39fc47685
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/329419
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed