WifiConnectivityManagerTest: exponential backoff periodic scan

Add a couple of unit tests to cover the periodic scan exponential
backoff feature.

Extended MockAlarmManager class such that users can query a
pending alarm's trigger time.

Bug: 28750989
Change-Id: I9520477180786fce2937e5fa87f790f60f12a3da
3 files changed
tree: 252ce9e1815ac15864bcafa64f6327d5fda6b1ae
  1. service/