Add a skeleton to support battery configucation backup/restore

Bug: 192523697
Test: make SettingsRoboTests
Change-Id: I559eed40b05b73e7af5e091115afb11c4ba51068

src/com/android/settings/backup/SettingsBackupHelper.java

@@ -22,6 +22,7 @@ import android.app.backup.BackupDataOutput;
 import android.app.backup.BackupHelper;
 import android.os.ParcelFileDescriptor;
 
+import com.android.settings.fuelgauge.BatteryBackupHelper;
 import com.android.settings.shortcut.CreateShortcutPreferenceController;
 
 import java.io.FileInputStream;
@@ -37,6 +38,7 @@ public class SettingsBackupHelper extends BackupAgentHelper {
     public void onCreate() {
         super.onCreate();
         addHelper("no-op", new NoOpHelper());
+        addHelper(BatteryBackupHelper.TAG, new BatteryBackupHelper(this));
     }
 
     @Override

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

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package com.android.settings.fuelgauge;
+
+import android.app.backup.BackupDataInputStream;
+import android.app.backup.BackupDataOutput;
+import android.app.backup.BackupHelper;
+import android.content.Context;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+
+/** An implementation to backup and restore battery configurations. */
+public final class BatteryBackupHelper implements BackupHelper {
+    /** An inditifier for {@link BackupHelper}. */
+    public static final String TAG = "BatteryBackupHelper";
+
+    private final Context mContext;
+
+    public BatteryBackupHelper(Context context) {
+        mContext = context;
+    }
+
+    @Override
+    public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
+            ParcelFileDescriptor newState) {
+        Log.d(TAG, "performBackup()");
+    }
+
+    @Override
+    public void restoreEntity(BackupDataInputStream data) {
+        Log.d(TAG, "restoreEntity()");
+    }
+
+    @Override
+    public void writeNewStateDescription(ParcelFileDescriptor newState) {
+    }
+}

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

@@ -40,7 +40,8 @@ public class BatteryDiffEntry {
     // Caches app label and icon to improve loading performance.
     static final Map<String, BatteryEntry.NameAndIcon> sResourceCache = new HashMap<>();
     // Whether a specific item is valid to launch restriction page?
-    static final Map<String, Boolean> sValidForRestriction = new HashMap<>();
+    @VisibleForTesting(otherwise = VisibleForTesting.PACKAGE_PRIVATE)
+    public static final Map<String, Boolean> sValidForRestriction = new HashMap<>();
 
     /** A comparator for {@link BatteryDiffEntry} based on consumed percentage. */
     public static final Comparator<BatteryDiffEntry> COMPARATOR =
@@ -339,7 +340,8 @@ public class BatteryDiffEntry {
         return builder.toString();
     }
 
-    static void clearCache() {
+    /** Clears app icon and label cache data. */
+    public static void clearCache() {
         sResourceCache.clear();
         sValidForRestriction.clear();
     }