onAccountsUpdated shouldn't be called back after listener unregistered

There is a problem of AccountManager that onAccountsUpdated() is
called back even after the OnAccountsUpdatedListener is unregistered.
It may cause application crash.

For example, when rotating a tablet 180 degree with Settings apk
running, com.android.settings.Settings is re-launched 2 times
successively. (Destroy->Create->Destroy->Create)
It repeats adding&removing OnAccountUpdatedListener.

When dialog was being opened in the following cases,
NullPointerException at BackStackRecord.getBreadCrumbTitle()
was happened on 10 inch tablet which has 2 panes on Settings.
* Settings > Language&input > Language
* Settings > Language & input > Text-to-speech output > Speech rate
* Settings > Wi-Fi > Menu > Advanced > Keep Wi-Fi on during sleep
* Settings > Wi-Fi > Menu > Wi-Fi Direct > Rename device

This fix prevents the undesirable callback.

Change-Id: I081f69c90539cca821cf686b4587495135f375e4
Fix to NullPointerException when activity is relaunched

When ChooseTypeAndAccountActivity is relaunched and resumed
by ActivityManager a call is made to onActivityResult without
first triggering onResume. This leads to mAccounts object
still being null.

Fixed by properly setting mAccounts object if it is null prior
to use after function onCreate has been called.

Change-Id: Ife7e1e052c473970d923fa43ee6189eb62a1113b
fwbs: Manual update from cm.

This is really bad, but rebasing and merging to get caught up would
take days.

Change-Id: Ib9e35b5abbecebca4831965dabab6b0358860ad1