The Ninth Circuit has held that an expunged California conviction remains a conviction for immigration purposes. It further held that a grant of probation is a sufficient restraint on liberty to qualify as a conviction as defined in the Immigration and Nationality Act.
The full text of Reyes v. Lynch can be found here:
http://cdn.ca9.uscourts.gov/datastore/opinions/2016/08/25/14-73510.pdf