Prevent accessibility focus on detached chipbar views.

The accessibility focus request at the end of the chipbar's "view in"
animation is now guarded by a check to ensure the view is still attached
to the window. This prevents issues where focus is requested on a view
that has already been removed from the window hierarchy. This CL was
initially generated by Gemini.

Fixes: 395114221
Flag: NONE bug fix
Test: Presubmits are sufficient
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:e66055b5a4cd63bedd4be239f6bc10cff52e16d1
Merged-In: Ibde56a802989196459ac60890048f69e22290dd7
Change-Id: Ibde56a802989196459ac60890048f69e22290dd7