Update wakelock detector

1. Use new API: getSubTimer().getTotalDurationMsLocked(), which returns
the wakelock running time in the background.
2. Add code to detect whether app is currently holding wakelocks, by
using API: getCurrentDurationMsLocked

Bug: 38233034
Test: RunSettingsRoboTests
Change-Id: If69b751acf5741ff8df2c905642c008a0a2b32e6
2 files changed