1. The active window for accessibility purposes is the either the
window the user is touching or the window that has input focus. We
were using the touch exploration gesture end event to figure
when the user stops touching the screen so we can set the active
window to the input focused one. However, we do not send such
gesture end if the user does not touch explore. If the user only
taps we do not consider this touch exploring. We now have dedicated
accessibility events for first and last touch and this change uses
them as a guide when to update the active window.
bug:6523219
Change-Id: I6262c0c5f408b02dbaa127664e4b426935d7f81f
76c0dd4827