Fix #2228604

* Fix anouther in a series of Exceptions that can occur if SyncManager
  is shut down abnormally.  These tend to happen runnings tests, and
  nowhere else.

Bug: 2228604
Change-Id: I064f11017431c1f1a73e8040dbc174f5ba03d7de

src/com/android/exchange/SyncManager.java

@@ -1625,6 +1625,7 @@ public class SyncManager extends Service implements Runnable {
 
         // Start up threads that need it; use a query which finds eas mailboxes where the
         // the sync interval is not "never".  This is the set of mailboxes that we control
+        if (mAccountObserver == null) return nextWait;
         Cursor c = getContentResolver().query(Mailbox.CONTENT_URI, Mailbox.CONTENT_PROJECTION,
                 mAccountObserver.getSyncableEasMailboxWhere(), null, null);