test for valid mips before setting on image

We seed the builder with the imageinfo of an image, but after it is
built we then have to "attach" it to an image (or more than one).

Check that the mip chain is compatible with the parent image we are
attaching to.


Change-Id: Iead6aee54861fdd4910f38f89a0364ed80c341d8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/305680
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
4 files changed