healthd: add optional current_now and charge_counter to tracked state

uA and uAh units are converted to mA and mAh.

If current_now is present, add it to the heartbeat log (c=nnn).

Change-Id: I2b5fe7b4505c98ca2d11c3f94564c1c38493c8b9
diff --git a/healthd/BatteryMonitor.h b/healthd/BatteryMonitor.h
index df0920b..ff1ea1e 100644
--- a/healthd/BatteryMonitor.h
+++ b/healthd/BatteryMonitor.h
@@ -49,6 +49,8 @@
     String8 mBatteryVoltagePath;
     String8 mBatteryTemperaturePath;
     String8 mBatteryTechnologyPath;
+    String8 mBatteryCurrentNowPath;
+    String8 mBatteryChargeCounterPath;
 
     Vector<String8> mChargerNames;