2D Recents: Fix issue with undocking only one task

While there's only one task and we undock it, it's not in the Recents
task list. In this change, we just reset the transform and return it.

Test: Checked that Recents works properly while docking and undocking a
task and it's the only task running.
Bug: 32101881

Change-Id: I1207b546ff2864018c8d9bf2520f4690762b2d27

packages/SystemUI/src/com/android/systemui/recents/views/grid/TaskGridLayoutAlgorithm.java

@@ -147,6 +147,10 @@ public class TaskGridLayoutAlgorithm  {
      */
     public TaskViewTransform getTransform(int taskIndex, int taskCount,
         TaskViewTransform transformOut, TaskStackLayoutAlgorithm stackLayout) {
+        if (taskCount == 0) {
+            transformOut.reset();
+            return transformOut;
+        }
 
         TaskGridRectInfo gridInfo = mTaskGridRectInfoList[taskCount - 1];
         mTaskGridRect.set(gridInfo.size);
@@ -162,7 +166,7 @@ public class TaskGridLayoutAlgorithm  {
 
         // We also need to invert the index in order to display the most recent tasks first.
         int taskLayoutIndex = taskCount - taskIndex - 1;
-        boolean isTaskViewVisible = (taskLayoutIndex < MAX_LAYOUT_TASK_COUNT);
+        boolean isTaskViewVisible = taskLayoutIndex < MAX_LAYOUT_TASK_COUNT;
 
         // Fill out the transform
         transformOut.scale = 1f;