The same lists of extra items stored in BgModelData are also stored in
UI components. This is causing ConcurrentModificationExceptions. The
solution is to clone these lists or mark them as immutable before storing
them in their respective components.
Bug: 206918543
Test: Verified that crash no longer occurs after fix.
Change-Id: I571a2c451af58137aa7513b372b6a8ecf9bd3ff6
Make sure that the ArrayList cannot be cleared on the model thread while
it is being used on the UI thread to render a launcher preview.
Test: Manual
Fix: 210123588
Change-Id: I5a47cb3f28f5ac9e400f6ae535e410c345e14ee1