This patch adds basic logging to NsdManager and NsdService, and improves
the facilities for pretty printing the event ids defined in NsdManager.
It also includes a few minor cleanups:
- adding 'final' on effectively final instance variables of NsdManager
and NsdService.
- similarly, adding 'static' on effectively static class fields.
- regrouping instance variables together.
Test: no functional changes
Bug: 33074219
Change-Id: I360d539e73cc8e4b45d4e0d20b2e345455fdb10c
32be63d083