Merge "Merge "Resolve 3 inconsistencies in accessibility button API - Unify...

Merge "Merge "Resolve 3 inconsistencies in accessibility button API - Unify logic for detecting availability of the accessibility button - Ensure the initial visibility state is propagated to A11yMS - Ensure services only receive availability callbacks for changes" into oc-dev am: 4ab690a5 am: 5f485cab" into oc-dr1-dev-plus-aosp
am: 04f887a8

Change-Id: I7bfae794e74e2a2ba93871d513f9437583b3c709