Skip cursor loader if not needed

The cursor loader was being started when the battery prediction
feature was not enabled. This could lead to null pointers because
it was not possible to provide it with a valid URI which would
make the CursorLoader unhappy. This CL makes it so we just skip
the CursorLoader initialization entirely when we know the feature
is disabled so we don't have this issue. It also includes a test
to make sure this does not regress.

Test: Robotests
Bug: 38371686
Change-Id: I4f6f6278bbc16668bca0b51fcc7e30f27a9e216f

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

@@ -106,7 +106,8 @@ public class PowerUsageSummary extends PowerUsageBase implements
 
     @VisibleForTesting
     static final int ANOMALY_LOADER = 1;
-    private static final int BATTERY_ESTIMATE_LOADER = 2;
+    @VisibleForTesting
+    static final int BATTERY_ESTIMATE_LOADER = 2;
     private static final int MENU_STATS_TYPE = Menu.FIRST;
     @VisibleForTesting
     static final int MENU_HIGH_POWER_APPS = Menu.FIRST + 3;
@@ -173,6 +174,7 @@ public class PowerUsageSummary extends PowerUsageBase implements
                 @Override
                 public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
                     final Uri queryUri = mPowerFeatureProvider.getEnhancedBatteryPredictionUri();
+
                     return new CursorLoader(getContext(), queryUri, null, null, null, null);
                 }
 
@@ -221,10 +223,7 @@ public class PowerUsageSummary extends PowerUsageBase implements
         mAnomalySparseArray = new SparseArray<>();
 
         initFeatureProvider();
-        if (mPowerFeatureProvider != null) {
+        initializeBatteryEstimateLoader();
-            getLoaderManager().initLoader(BATTERY_ESTIMATE_LOADER, Bundle.EMPTY,
-                    mBatteryPredictionLoaderCallbacks);
-        }
     }
 
     @Override
@@ -761,6 +760,15 @@ public class PowerUsageSummary extends PowerUsageBase implements
         }
     }
 
+    @VisibleForTesting
+    void initializeBatteryEstimateLoader() {
+        if (mPowerFeatureProvider != null
+                && mPowerFeatureProvider.isEnhancedBatteryPredictionEnabled(getContext())) {
+            getLoaderManager().initLoader(BATTERY_ESTIMATE_LOADER, Bundle.EMPTY,
+                    mBatteryPredictionLoaderCallbacks);
+        }
+    }
+
     private static List<BatterySipper> getFakeStats() {
         ArrayList<BatterySipper> stats = new ArrayList<>();
         float use = 5;

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

@@ -530,6 +530,18 @@ public class PowerUsageSummaryTest {
         mFragment.mBatteryPredictionLoaderCallbacks.onLoadFinished(null, null);
     }
 
+    @Test
+    public void testOnCreate_BatteryPredictionSkippedWhenDisabled() {
+        PowerUsageFeatureProvider provider = mFeatureFactory.getPowerUsageFeatureProvider(mContext);
+        when(provider.isEnhancedBatteryPredictionEnabled(any())).thenReturn(false);
+        mFragment.mPowerFeatureProvider = provider;
+        doReturn(mLoaderManager).when(mFragment).getLoaderManager();
+        mFragment.initializeBatteryEstimateLoader();
+
+        verify(mLoaderManager, never()).initLoader(eq(PowerUsageSummary.BATTERY_ESTIMATE_LOADER),
+                eq(Bundle.EMPTY), any());
+    }
+
     @Test
     public void testInitAnomalyDetectionIfPossible_detectionEnabled_init() {
         when(mFeatureFactory.powerUsageFeatureProvider.isAnomalyDetectionEnabled()).thenReturn(