Fix some bugs around stack parenting
1. Don't unfreeze/clear snapshot in onChildVisibilityRequested
if its becoming visible... this situation means that the
container changed via going invis + made vis again (which
is a result of a single transaction reparenting + changing
mode).
2. Fixed a crash in applyTransaction where if you tried to
reparent a task that was already on the display to null,
it would call reparent rather than re-order. DisplayArea
reparent crashes if the task is already a child.
Bug: 151881448
Test: Added some tests
Change-Id: Ieb5794b365bc256ec02a95a4abbf16d9a28753bd
3 files changed