Since this class implements equals() and hashCode() it should either be
final or handle subclasses in equals(); given this is unlikely to be
subclassed, making it final is the simpler option.
The AccessibilityViewEmbedder was not delegating a11y events coming virtual nodes(of the embedded view) that were not previously traversed by the a11y framework.
It turns out the a11y framework might leave parts of the tree untraversed in some circumstances, changed the behavior to create an originId<-->flutterId mapping on the fly when an event is delegated from a not previously traversed node.
Fixesflutter/flutter#30010.
Delegate a11y events and action to/from embedded Android platfrom views.
This handles delegation of:
* AccessibilityNodeProvider#performAction
* ViewGroup#requestSendAccessibilityEvent
* View#onHoverEvent
Additionally updates the currently input accessibility focused node state that is
tracked by the a11y bridge when an embedded view's node is focused.
This PR mirrors virtual a11y tree of embedded platform views in the Flutter
a11y tree.
Non virtual hierarchies are not currently supported.
Only works on Android versions earlier than Android P as it relies on
reflection access to hidden system APIs which cannot be done starting
Android P.
A11y is not yet working as we also need to delegate a11y events from the
platform view to the FlutterView. This will be done in a following PR to
keep the change size a little saner.
