Misc small changes in Session.java.

* Move helper methods to static methods in Helper.java
* Add documentation on ambiguous methods.
* Rename method to end with *Locked for consistency.

Bug: 162357598
Test: atest CtsAutoFillServiceTestCases
Change-Id: I1b2f788a74fa16f566520f5e83c2df21ffbca2dc
4 files changed