Never store battery stats for cache

In PowerUsageBase, it will store battery stats if it has a configuration
change, which will make BatteryStatsLoaderHelper never get the correct
battery stats because it uses Bundle.EMPTY as the bundle message.

This cl:
1. Remove the store action even though it is configuration change.
2. Always use null to get battery stats
3. Always start a battery status check in register()

Bug: 63658232
Test: RunSettingsRoboTests
Change-Id: Ifbf970c63378ed66dddcdae4d952b7d1fd84216a

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

@@ -32,7 +32,11 @@ import org.robolectric.RuntimeEnvironment;
 import org.robolectric.annotation.Config;
 
 import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
 
 @RunWith(SettingsRobolectricTestRunner.class)
@@ -52,7 +56,7 @@ public class BatteryBroadcastReceiverTest {
     @Before
     public void setUp() {
         MockitoAnnotations.initMocks(this);
-        mContext = RuntimeEnvironment.application;
+        mContext = spy(RuntimeEnvironment.application);
 
         mBatteryBroadcastReceiver = new BatteryBroadcastReceiver(mContext);
         mBatteryBroadcastReceiver.mBatteryLevel = BATTERY_INIT_LEVEL;
@@ -92,4 +96,17 @@ public class BatteryBroadcastReceiverTest {
         verify(mBatteryListener, never()).onBatteryChanged();
     }
 
+    @Test
+    public void testRegister_updateBatteryStatus() {
+        doReturn(mChargingIntent).when(mContext).registerReceiver(any(), any());
+
+        mBatteryBroadcastReceiver.register();
+
+        assertThat(mBatteryBroadcastReceiver.mBatteryLevel).isEqualTo(
+                Utils.getBatteryPercentage(mChargingIntent));
+        assertThat(mBatteryBroadcastReceiver.mBatteryStatus).isEqualTo(
+                Utils.getBatteryStatus(mContext.getResources(), mChargingIntent));
+        verify(mBatteryListener).onBatteryChanged();
+    }
+
 }