Handle multiple AccessibilityEvent parsing for scrolling

Refactored to handle Accessibility events into their corresponding
Predicate types.

Fixed scrollSwipe to allow it to receive all relevant accessibility
events so to determine current scroll position. This required the
reading the last scroll event from a list of events.

bug:8099066

Change-Id: If1770b5fc7b56da03dd16ec3f8e5fe4686f7580b
3 files changed