Introduce initial A-Z app drawer to taskbar.

Invoking the drawer is currently hooked up to tapping empty space on the
taskbar. Apps can be launched, and drag-n-drop split screen works. The
drawer can only be dismissed by acting on an app icon or tapping the
taskbar again.

Test: Manual
Bug: 204696617
Change-Id: I7c5fdbc7d54d8209f6f15ef80bfeb5e9b80cf647

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

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2022 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 android.content.Context;
+import android.util.AttributeSet;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.WindowInsets;
+
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.android.launcher3.allapps.AllAppsGridAdapter;
+import com.android.launcher3.allapps.BaseAllAppsContainerView;
+import com.android.launcher3.allapps.search.SearchAdapterProvider;
+
+/** All apps container accessible from taskbar. */
+public class TaskbarAllAppsContainerView extends BaseAllAppsContainerView<TaskbarActivityContext> {
+    public TaskbarAllAppsContainerView(Context context) {
+        this(context, null);
+    }
+
+    public TaskbarAllAppsContainerView(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public TaskbarAllAppsContainerView(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    @Override
+    protected SearchAdapterProvider<?> createMainAdapterProvider() {
+        // Task bar all apps does not yet support search, so this implementation is minimal.
+        return new SearchAdapterProvider<TaskbarActivityContext>(mActivityContext) {
+            @Override
+            public boolean launchHighlightedItem() {
+                return false;
+            }
+
+            @Override
+            public View getHighlightedItem() {
+                return null;
+            }
+
+            @Override
+            public RecyclerView.ItemDecoration getDecorator() {
+                return null;
+            }
+
+            @Override
+            public boolean isViewSupported(int viewType) {
+                return false;
+            }
+
+            @Override
+            public void onBindView(AllAppsGridAdapter.ViewHolder holder, int position) { }
+
+            @Override
+            public AllAppsGridAdapter.ViewHolder onCreateViewHolder(LayoutInflater layoutInflater,
+                    ViewGroup parent, int viewType) {
+                return null;
+            }
+        };
+    }
+
+    @Override
+    public WindowInsets onApplyWindowInsets(WindowInsets insets) {
+        // TODO(b/204696617): Switch to status bar insets once they work.
+        setInsets(insets.getInsets(WindowInsets.Type.tappableElement()).toRect());
+        return super.onApplyWindowInsets(insets);
+    }
+}