am ba6409f1: Merge change 4706 into donut

Merge commit 'ba6409f1f69db7dfa16d5b914d2bc41a3aa43caf'

* commit 'ba6409f1f69db7dfa16d5b914d2bc41a3aa43caf':
  Add a new checkin server flag for Vending Machine heartbeats.