Prevent multiple calls to onDone() in AccountSetupOptions

* When "Done" is pressed in AccountSetupOptions and the Account is
  EAS, the finish() isn't called until an async method's callback
  is invoked (system account creation)
* This allowed the user to execute onDone() multiple times, each
  one of which would attempt to create an account
* The net effect was the referenced bug, which can manifest in a
  number of ugly ways
* The fix is to prevent multiple calls to onDone()

Bug: 2501574
Change-Id: I61057bbb8c1f85da07e83ed6c56474bfe4e23f6c
1 file changed