validate offsetToRestore

Bug: skia:7425
Change-Id: I6451058bc5194853440f08a053fb974bc8f377a2
Reviewed-on: https://skia-review.googlesource.com/95161
Commit-Queue: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
1 file changed