It now tracks all sample calls of a child (matrix, explicit coords,
pass through). There is now just one registerChild() call, and the
sampling pattern of that child is fully determined by the SampleUsage
parameter.
Change-Id: Iaadcd325fca64a59f24192aadd06923c66362181
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299875
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
