Update framework from androidx.

Changes included:
* 285c252: Updates and clarifications to GenericDocument comments.
* 3c2a58e: Updates and clarifications to SearchSpec/SearchResult comments.
* 764cec9: Cleanup locking strategy.

Test: Presubmit
Change-Id: I4e9954db7cc3f02cf7a30ee09cb5a4533641c585
17 files changed