The onSplitScreenInvoked was used to notify system ui to reset the
divider position before entering split screen. With
SplitScreenTaskOrganizer, WM Shell library could know the exact time
when entering/leaving split screen mode. Removes the legacy API and
resets divider position when leaving split screen mode.
Fix: 168869136
Test: atest WMShellTests
Test: atest SystemUITests
Test: manual check recents and split screen behavior
Change-Id: Id14925619d1ec7c014a3e306fd99ec3734f227da
Jerry Chang
44981eb88e