Improve Ganesh Protected content testing

I don't know why we had been skipping validation of the the created Protected SkImage.

Change-Id: I9a06eed4e5a9a42b52183f7657be7a726bb53177
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/783337
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed