Some accessibility events not sent from touch explorer if apps misbehave.

1. The touch explorer is relying on the hover exit accessibility event to be sent
   from the app's view tree before sending the exploration end and last touch
   accessibility events. However, if the app is buggy and does not send the hover
   exit event, then the interaction ending events are never sent. Now there is a
   timeout in which we wait for the hover exit accessibility event before sending
   the gesture end and last touch accessibility events. Hence, we are making a
   best effort to have a consistent event stream.

2. Sneaking in the new nine patch for the border around the magnified region
   since the current one is engineering art.

bug:7233616

Change-Id: Ie64f23659c25ab914565d50537b9a82bdc6a44a0