This reverts commit 2abf1c60cc.
We need the ability to register remote callbacks for persistent vr mode,
so vr flinger can register for persistent vr mode events.
Bug: 35885165
Test: Manually confirmed vr flinger can register and receive persistent
vr mode events.
Change-Id: I7713c4c8acae9a369fd0c06695ef712fddd12be8