Make sure we hold refs to sampled textures in d3d.

Change-Id: Id2542457a361963d7052674bc875a66bd59b48d9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/298676
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
3 files changed