Add BatteryInfo logging to settings

This Cl adds a few log statements to BatteryInfo to try
and determine what the bottleneck in the Battery Settings
Advanced page could be.

Test: robotests still pass
Bug: 62959645
Change-Id: I1ff712d97bc8be78873c63e187edbffa8e10cd21

src/com/android/settings/fuelgauge/BatteryUtils.java

@@ -285,6 +285,10 @@ public class BatteryUtils {
 
     }
 
+    public static void logRuntime(String tag, String message, long startTime) {
+        Log.d(tag, message + ": " + (System.currentTimeMillis() - startTime) + "ms");
+    }
+
     /**
      * Find package uid from package name
      *