First, getAccounts*() will now return all available accounts depending
on both GET_ACCOUNTS grants and signature matching. This is different
from before where a caller of getAccounts() would need GET_ACCOUNTS to
get any accounts, but if that same caller called getAccountsByType, they
might have gotten back accounts if they shared a signature with the same
developer.
Second, cleaned up some NPEs and javadoc.
This change was motivated by progress on the cts tests.
Change-Id: I2f36226780e074fdf58214b46de3b79d8319ace1
e7ed827a10