This is the topaz counterpart to
https://fuchsia-review.googlesource.com/c/fuchsia/+/277254.
This is a backwards-incompatible ABI change that will be landed together
with that CL. All clients have been migrated to be compatible with the
new ABI.
Change-Id: I07bb460ce3c6971eb671874db1f90e8c4906e656
Ported from Topaz tree.