Ensure ViewPager scroll event properties are properly set

- Previous behavior obtained an AccessibilityRecord and
  set the scroll position properties there, but then
  discarded the record.
- New behavior sets the properties by getting the record
  from the event.

b/27487654

Change-Id: I7a9bc21a6230fc9e361a9a5f5d3e9ce1abdf0c74
1 file changed