Simplify SkDrawTiler; check emtpy pixmap and overflow

Not sure whether this will fix b/77249109, but we can have a try.

Bug: b/77249109
Change-Id: Ia569cb130758dd0a63bfe2ecb29e61c75716c955
Reviewed-on: https://skia-review.googlesource.com/117460
Commit-Queue: Yuqian Li <liyuqian@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>
1 file changed