[Robustness] protect get battery stats from DeadSystemException

In some corner cases, we will receive the DeadSystemException from
BatteryStatService when invoking getBatteryUsageStats() method. Before
this issue is resolved by BatteryStatService team, we will add some
protections to avoid Settings app is crashed.

Bug: 195306545
Bug: 195467687
Test: make SettingsRoboTests
Change-Id: I75fcf63f4f69d86d6dce0e12bd4d738b1219ae47

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

@@ -25,6 +25,7 @@ import android.net.Uri;
 import android.os.Bundle;
 import android.os.Handler;
 import android.provider.Settings.Global;
+import android.util.Log;
 
 import androidx.annotation.VisibleForTesting;
 import androidx.loader.app.LoaderManager;
@@ -103,6 +104,10 @@ public class PowerUsageSummary extends PowerUsageBase implements
 
                 @Override
                 public void onLoadFinished(Loader<BatteryInfo> loader, BatteryInfo batteryInfo) {
+                    if (batteryInfo == null) {
+                        Log.w(TAG, "mBatteryInfoLoaderCallbacks: batteryInfo = null");
+                        return;
+                    }
                     mBatteryHeaderPreferenceController.updateHeaderPreference(batteryInfo);
                     mBatteryHeaderPreferenceController.updateHeaderByBatteryTips(
                             mBatteryTipPreferenceController.getCurrentBatteryTip(), batteryInfo);
@@ -126,6 +131,10 @@ public class PowerUsageSummary extends PowerUsageBase implements
                 @Override
                 public void onLoadFinished(Loader<List<BatteryTip>> loader,
                         List<BatteryTip> data) {
+                    if (mBatteryInfo == null) {
+                        Log.w(TAG, "mBatteryTipsCallbacks: batteryInfo = null");
+                        return;
+                    }
                     mBatteryTipPreferenceController.updateBatteryTips(data);
                     mBatteryHeaderPreferenceController.updateHeaderByBatteryTips(
                             mBatteryTipPreferenceController.getCurrentBatteryTip(), mBatteryInfo);