Add FutureTask approach in DashboardFragment

- Use the multiple tasks to enhance the controllers loading.

Bug: 137558156
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.dashboard
Change-Id: I629ff5dc81347cddf9762a87015b9b86b6a46e50

src/com/android/settings/dashboard/ControllerFutureTask.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2019 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.dashboard;
+
+import com.android.settingslib.core.AbstractPreferenceController;
+
+import java.util.concurrent.FutureTask;
+
+/**
+ *  {@link FutureTask} of the Controller.
+ */
+public class ControllerFutureTask extends FutureTask<Void> {
+    private final AbstractPreferenceController mController;
+
+    public ControllerFutureTask(ControllerTask task, Void result) {
+        super(task, result);
+        mController = task.getController();
+    }
+
+    AbstractPreferenceController getController() {
+        return mController;
+    }
+}