[Android] Dispose the collection view item adapter

[kvpt]

Description of Change

The adapter was not dispose which was causing a leak with the item source.

Issues Resolved

• fixes [CollectionView, Android] DisposedObjectException thrown when adding elements to ItemsSource after having disposed CollectionView containing EmptyView #6427

API Changes

None

Platforms Affected

• Android

Behavioral/Visual Changes

None

Before/After Screenshots

Not applicable

Testing Procedure

Like all other garbage collection issue, it very difficult to produce a reliable reproduction.
I tried to make a reproduction case from the elements of the issue #6427 without success.

PR Checklist

• Has automated tests
• Rebased on top of the target branch at time of PR
• Changes adhere to coding standard

[kvpt]

I made a more correct fix.

I have modified two parts :

• In UpdateAdapter, Unwatch and Dispose the old adapter, this part was missing.
• In TearDownOldElement Unwatch and Dispose the adapter ItemsViewAdapter in all case.

The problem in this one was that the adapter was retrieved by the GetAdapter method, so if the adapter was previously swapped with the _emptyViewAdapter the GetAdapter method returned _emptyViewAdapter and not ItemsViewAdapter, so ItemsViewAdapter was never disposed.
_emptyViewAdapter has nothing to dispose so the only adapter we want to dispose is not the current one, it is ItemsViewAdapter.

I also noticed an inconsistency in the naming of the callbacks, don't know if it's too late or not to be changed.

• LayoutOnPropertyChanged => OnLayoutPropertyChanged
• ScrollToRequested => OnScrollToRequested

[hartez]

nconsistency in the naming of the callbacks, don't know if it's too late or not to be changed.

I we were going to change it, that would need to happen in a different PR. PRs need to be focused.