Convert booleans in NAI to timestamps

These timestamps will be useful for debugging issues where
debuggers need to know what happened to long-lived networks,
where logcat doesn't span long enough.

These timestamps are also likely to be useful in the future,
in particular for metrics.

Test: FrameworksNetTests
Change-Id: I8f46ce92e2ab301fa32e18e714a43a4130719199
6 files changed