Move logic from SavedAccessPoint fragment to controller

Change-Id: Ic54e536f97490cec1746fa58c42ec55b60d17f0e
Fixes: 64806699
Test: robotests

src/com/android/settings/utils/PreferenceGroupChildrenCache.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2018 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.utils;
+
+import android.text.TextUtils;
+import android.util.ArrayMap;
+
+import androidx.preference.Preference;
+import androidx.preference.PreferenceGroup;
+
+/**
+ * Class that helps track which {@link Preference}s in a {@link PreferenceGroup} are still being
+ * used, and remove unused ones.
+ */
+public class PreferenceGroupChildrenCache {
+
+    private ArrayMap<String, Preference> mPreferenceCache;
+
+    public void cacheRemoveAllPrefs(PreferenceGroup group) {
+        mPreferenceCache = new ArrayMap<>();
+        final int N = group.getPreferenceCount();
+        for (int i = 0; i < N; i++) {
+            Preference p = group.getPreference(i);
+            if (TextUtils.isEmpty(p.getKey())) {
+                continue;
+            }
+            mPreferenceCache.put(p.getKey(), p);
+        }
+    }
+
+    public void removeCachedPrefs(PreferenceGroup group) {
+        for (Preference p : mPreferenceCache.values()) {
+            group.removePreference(p);
+        }
+        mPreferenceCache = null;
+    }
+
+    public Preference getCachedPreference(String key) {
+        return mPreferenceCache != null ? mPreferenceCache.remove(key) : null;
+    }
+
+    public int getCachedCount() {
+        return mPreferenceCache != null ? mPreferenceCache.size() : 0;
+    }
+}