signal on bad picture op, simplify other ops

Bug: skia:7569
Change-Id: Iec5d7472e6cdb0fe87a634209c5349085c9ebfbd
Reviewed-on: https://skia-review.googlesource.com/102424
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed