Base split action on focusedTaskView instead of runningTaskView

* getRunningTaskView() is null when rotating device,
only valid when swiping up to overview
* focusedTaskView() correctly set in both cases

Fixes: 199461147
Test: Bug doesn't repro
Change-Id: Ib39c1f6f05b3cd5f72c13facc6b8000346896476
1 file changed