Adopt robolectric 3.6.1

Bug: 71596155
Test: make RunSettingsRoboTests
Change-Id: I46362bae1e3ddd3ce19ade1c93250d272f3366e6

tests/robotests/src/com/android/settings/fuelgauge/BatteryInfoLoaderTest.java

@@ -76,6 +76,7 @@ public class BatteryInfoLoaderTest {
     @Test
     public void test_loadInBackground_dischargingOldEstimate_dischargingLabelNotNull() {
         BatteryInfoLoader loader = new BatteryInfoLoader(mContext, mHelper);
+        loader.batteryUtils = new BatteryUtils(mContext);
 
         BatteryInfo info = loader.loadInBackground();