Deprecate AppListPreference and AppListPrefWithSettings

- Convert ManageAssist into DashboardFragment
- Convert default assist pref to DefaultAppPickerFragment
- Add PreferenceController for each pref
- Add tests

Bug: 35203386
Test: make RunSettingsRoboTests

Change-Id: I0350a06cae7457809fb261e2d8ec99eda80cc50a

src/com/android/settings/applications/assist/AssistSettingObserver.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2017 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.applications.assist;
+
+import android.content.ContentResolver;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.os.Handler;
+import android.provider.Settings;
+
+import java.util.List;
+
+public abstract class AssistSettingObserver extends ContentObserver {
+
+    private final Uri ASSIST_URI =
+            Settings.Secure.getUriFor(Settings.Secure.ASSISTANT);
+
+    public AssistSettingObserver() {
+        super(new Handler());
+    }
+
+    public void register(ContentResolver cr, boolean register) {
+        if (register) {
+            cr.registerContentObserver(ASSIST_URI, false, this);
+            final List<Uri> settingUri = getSettingUris();
+            if (settingUri != null) {
+                for (Uri uri : settingUri)
+                cr.registerContentObserver(uri, false, this);
+            }
+        } else {
+            cr.unregisterContentObserver(this);
+        }
+    }
+
+    @Override
+    public void onChange(boolean selfChange, Uri uri) {
+        super.onChange(selfChange, uri);
+        boolean shouldUpdatePreference = false;
+        final List<Uri> settingUri = getSettingUris();
+        if (ASSIST_URI.equals(uri) || (settingUri != null && settingUri.contains(uri))) {
+            shouldUpdatePreference = true;
+        }
+        if (shouldUpdatePreference) {
+            onSettingChange();
+        }
+    }
+
+    protected abstract List<Uri> getSettingUris();
+
+    public abstract void onSettingChange();
+}