ActiveDisplay: clean up package member visibility and trivial funcitons

Anything in the outer class that is accessed by an inner class should not be labeled
private.  This inlines some trivial functions and moves some code to the inner classes
that uses it also.  It also makes the screen state boolean volatile which fixes the
issue with the screen not turning on occassionally when a notification is received or
pocket mode is activated.

Change-Id: Ia163bf1d0d36dd859003f355e08e717bca8b61a2
Merge "ActiveDisplay: clean up package member visibility and trivial funcitons" into kk44