tree c8643bfdc3fca156d5e8055de5d7890803701c30
parent a0f863d4fba1d70145a1626752741cd0804e8674
author Jack Yu <jackyu@google.com> 1517011397 -0800
committer Jack Yu <jackyu@google.com> 1517016501 +0000

Added nullable callback support

Sometimes data service clients do not care the result of the
requests so they pass null callback. In this case the data service
should handle it.

Test: Manual
Bug: 64132030
Change-Id: Ib188994fed4e708de875a24d5386a74a8f6db4dd