Add a button for floating tasks to taskbar (behind a flag)

Test: manual - build launcher3, enable the feature flag on tablet with
               a valid app installed, open an app, observe that there
               is NO button in taskbar because launcher3 doesn't have
               populated config
Bug: 237678727
Change-Id: Ic261608898eb9a9220cffacd0c6060a32c10a74f

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

@@ -0,0 +1,51 @@
+/*
+ * 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.graphics.Bitmap;
+import android.util.AttributeSet;
+import android.view.ContextThemeWrapper;
+
+import com.android.launcher3.BubbleTextView;
+import com.android.launcher3.LauncherAppState;
+import com.android.launcher3.R;
+import com.android.launcher3.icons.FastBitmapDrawable;
+
+/**
+ * Button in Taskbar that opens something in a floating task.
+ */
+public class LaunchFloatingTaskButton extends BubbleTextView {
+
+    public LaunchFloatingTaskButton(Context context) {
+        this(context, null);
+    }
+
+    public LaunchFloatingTaskButton(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public LaunchFloatingTaskButton(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+
+        Context theme = new ContextThemeWrapper(context, R.style.AllAppsButtonTheme);
+        Bitmap bitmap = LauncherAppState.getInstance(context).getIconCache().getIconFactory()
+                .createScaledBitmapWithShadow(
+                        theme.getDrawable(R.drawable.ic_floating_task_button));
+        setIcon(new FastBitmapDrawable(bitmap));
+    }
+}