Fix bug 4901592 Do not drill-in to inbox by default

If the initial mailbox has child mailboxes, we should show the drilled-in
view by default, EXCEPT if the initial mailbox is inbox, in which case
we want to show the root view.

(And we drill-in if the user taps Inbox.)

Bug 4901592

Change-Id: Idc1462030cf8d971dd4dcbba647ac3a64cab6819
1 file changed