Reorganize taskbar controllers

Organize existing properties as follows:
- TaskbarViewController contains properties affecting TaskbarView (though child icons are still supplied by TaskbarHotseatController)
- TaskbarDragLayerController contains properties related to TaskbarDragLayer itself
- Renamed NavbarButtonUiController to NavbarButtonsViewController, following the pattern of TaskbarViewController and TaskbarDragLayerController
- TaskbarControllers contains the different controllers to make it easier to construct, initialize, destroy, and pass them around
- Removed TaskbarIconController as its responsibilities were moved to more specific controllers

Test: compiles and runs, manually tested
Bug: 187353581
Change-Id: Idccd95d47117101bf9617e5532a5b87635d2b8f6

quickstep/src/com/android/launcher3/taskbar/TaskbarControllers.java

@@ -0,0 +1,76 @@
+/*
+ * 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.launcher3.taskbar;
+
+import androidx.annotation.NonNull;
+
+import com.android.launcher3.taskbar.contextual.RotationButtonController;
+
+/**
+ * Hosts various taskbar controllers to facilitate passing between one another.
+ */
+public class TaskbarControllers {
+
+    public final TaskbarActivityContext taskbarActivityContext;
+    public final TaskbarDragController taskbarDragController;
+    public final TaskbarNavButtonController navButtonController;
+    public final NavbarButtonsViewController navbarButtonsViewController;
+    public final RotationButtonController rotationButtonController;
+    public final TaskbarDragLayerController taskbarDragLayerController;
+    public final TaskbarViewController taskbarViewController;
+
+    /** Do not store this controller, as it may change at runtime. */
+    @NonNull public TaskbarUIController uiController = TaskbarUIController.DEFAULT;
+
+    public TaskbarControllers(TaskbarActivityContext taskbarActivityContext,
+            TaskbarDragController taskbarDragController,
+            TaskbarNavButtonController navButtonController,
+            NavbarButtonsViewController navbarButtonsViewController,
+            RotationButtonController rotationButtonController,
+            TaskbarDragLayerController taskbarDragLayerController,
+            TaskbarViewController taskbarViewController) {
+        this.taskbarActivityContext = taskbarActivityContext;
+        this.taskbarDragController = taskbarDragController;
+        this.navButtonController = navButtonController;
+        this.navbarButtonsViewController = navbarButtonsViewController;
+        this.rotationButtonController = rotationButtonController;
+        this.taskbarDragLayerController = taskbarDragLayerController;
+        this.taskbarViewController = taskbarViewController;
+    }
+
+    /**
+     * Initializes all controllers. Note that controllers can now reference each other through this
+     * TaskbarControllers instance, but should be careful to only access things that were created
+     * in constructors for now, as some controllers may still be waiting for init().
+     */
+    public void init() {
+        navbarButtonsViewController.init(this);
+        if (taskbarActivityContext.canShowNavButtons()) {
+            rotationButtonController.init();
+        }
+        taskbarDragLayerController.init(this);
+        taskbarViewController.init(this);
+    }
+
+    /**
+     * Cleans up all controllers.
+     */
+    public void onDestroy() {
+        uiController.onDestroy();
+        rotationButtonController.onDestroy();
+        taskbarDragLayerController.onDestroy();
+    }
+}