base

Read autoclick delay from settings

Instead of hardcoding autoclick delay, use
Settings.Secure.ACCESSIBILITY_AUTOCLICK_DELAY value.
Adds logic for observing the setting's changes and updating the delay
that should be used when scheduling automatical click.

BUG=23113412

Change-Id: Iffe3df0cb64ab28f13d2803d01d581280aedf422