Do not add a stub TaskView unless there is no running TaskView.
And add the TaskView type checking while getting the running TaskView
from the given [GroupedTaskInfo].
Bug: 407120863
Test: 1. Change to a 3P launcher (e.g., Nova Launcher), clear recents
task, then swipe up from home screen, verified that
"No recent items" is shown without having a transparent
home TaskView.
2. Drag a window inside the desk to be a fullscreen one,
then swipe up, verified that it works correctly.
3. Swiping up from fullscreen or desk tasks works correctly.
Flag: com.android.window.flags.enable_multiple_desktops_frontend
Flag: com.android.window.flags.enable_multiple_desktops_backend
Change-Id: I73f8b3310b4c66fdd3dd9cc5cd95418196279893
minch
38b14021a9