Guard against NPE in equals checks.

Update State test to cover different conditions separately.
Update DirectoryInfo test to best practices.
Update RootInfo to follow DirectoryInfo equals pattern.
Also, allow null cursors from Model...since they happen...I seen it mahself.

Bug: 27118725
Change-Id: Id0a0be053b91c887a745bfca5416e64f0edba995
5 files changed