Fix uncommanded exit from MessageList with 2+ accounts

* When you have 2 or more accounts configured, MessageList gets confused.
* If you are viewing a mailbox from account A, and account B does a
  background sync, MessageList gets confused by the reports coming back
  from the Controller.  It gives up and returns to the Accounts list.
* This change adds a check for the current account and ignores the
  MessageList updates if we weren't actually waiting for them.
* To test the positive case for this code (make sure we didn't break it),
  verify that the inbox on an IMAP account is displayed properly
  immediately after you add it.

Bug: 2619513
Change-Id: Ib31254b4099ba6b7922b06d42e2b7928551e4fb2
1 file changed