Validating non-empty authority and accountType

Code was check for null but empty strings are also not allowed.

Test: Manually installed the app causing the bootloop before the fix.
Rebooted the device to force schedule a sync and observed no crash.

Fixes: 19893917
Change-Id: If13aa0ac4cb3358da4b8e2bc62cb277d5248edaa
1 file changed