Adding initial protos for batterystats dump.

Timer is the basic stat tracking object that's used for a lot of the
data in batterystats.
ControllerActivity data is tracked both per uid and for the entire
system, so it makes sense to define it now independently.
For the BatteryStatsHelper change: there's a small window of time after
boot where getSystemService will return null. I ran into it.

BUG: 65750808
Test: flash device and check incident proto output
Change-Id: I15e7d046a43f76d5f53d05b5138ea40f42e19d59