Stay in the current task when a new desk is created

Bug: 401002178
Flag: com.android.window.flags.enable_multiple_desktops_frontend
Flag: com.android.window.flags.enable_multiple_desktops_backend
Test: manual create new desks
Change-Id: Iaa29c557a421d5c51b90aa808188d3cabec89143

quickstep/src/com/android/quickstep/views/RecentsView.java

@@ -7038,6 +7038,8 @@ public abstract class RecentsView<
             return;
         }
 
+        TaskView currentTaskView = getTaskViewAt(mCurrentPage);
+
         // We assume that a newly added desk is always empty and gets added to the left of the
         // `AddNewDesktopButton`.
         DesktopTaskView desktopTaskView =
@@ -7051,9 +7053,12 @@ public abstract class RecentsView<
 
         updateTaskSize();
         mUtils.updateChildTaskOrientations();
+        updateScrollSynchronously();
 
-        // TODO: b/401002178 - Recalculate the new current page such that the addition of the new
-        //  desk does not result in a change in the current scroll page.
+        // Set Current Page based on the stored TaskView.
+        if (currentTaskView != null) {
+            setCurrentPage(indexOfChild(currentTaskView));
+        }
     }
 
     @Override