Invoke close() method for BatteryUsageStats to close cursor window

invoke close() method for BatteryUsageStats to close cursor window,
since BatteryUsageStats will implement "Closeable" interface in T.
(from Dimitri's request)

Bug: 201229421
Test: make SettingsRoboTests
Change-Id: Ibfca404d00cce51405cffddb636f685869ac130b

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

@@ -405,6 +405,11 @@ public class BatteryUtils {
                 batteryUsageStats, estimate, elapsedRealtimeUs, false /* shortString */);
         BatteryUtils.logRuntime(tag, "BatteryInfoLoader.loadInBackground", startTime);
 
+        try {
+            batteryUsageStats.close();
+        } catch (Exception e) {
+            Log.e(TAG, "BatteryUsageStats.close() failed", e);
+        }
         return batteryInfo;
     }