Prevent null allowableAccounts from crashing

The javadoc for newChooseAccountIntent says that a null
value for the allowableAccounts parameter is valid and
an acceptable default. This CL makes sure that when this
parameter is null, a NullPointerException is not thrown.

Bug: 22475546
Change-Id: Ieb0d67dd02628e1ae5629499b3be3c6382efc9aa
1 file changed