Avoid possible nullptr dereference

We cherry-pick the appropriate part of
https://skia-review.googlesource.com/c/skia/+/279136 to rvc-dev
to make sure we don't have a nullptr dereference.  Since that
CLs is quite large, we chose to just make this small change
instead of introduce a large change.

Bug: 154661346
Test: TreeHugger
Change-Id: I01ac23547a345b1aed8048cd83cb7a1f1e36e331
Merged-In: I7c990413b7a966f6a330289552d4520be0f3d3d1
1 file changed