base

Fix touch accessibility in keyguard.

This changes the accessibility code to monitor state changes
and replace the touch listeners with click listeners when
touch exploration is enabled.

It also fixes a bug where the first touch on the camera was being
ignored by ensuring KeyguardTouchDelegate has started the service
by the time the button is touched.

Bug 10991981

Change-Id: I7c4bf01f9bfa10f54cadb0809b6af526c5386af5