Final polish of the interrogation feature.

1. Added a new event type for notifying client accessibilitiy
   services for changes in the layout. The event is fired at
   most once for a given time frame and is delivered to clients
   only if it originates from the window that can be interrogated.

2. Exposed the findByText functionality in AccessibilityNodeInfo.
   This is very useful for an accessibility service since it allows
   searching for something the user knows is on the screen thus
   avoiding touch exploring the content. Touch exploring is
   excellent for learning the apps but knowing them search is
   much faster.

3. Fixed a bug causing an accessibiliby service not to receive
   the event source in case of more than one service is registered
   and one of them does not have paermission to interrogate the window.
   The same event was dispatched to multiple services but if one
   of them does not have interrogation permission the event is
   modified to remove the source causing subsequent serivices not
   to get the later.

4. Moved the getSource setSource methods to AccessibilityRecord
   instead in AccessibilityEvent.

5. Hiden some protected members in AccessibilityRecod which should
   not be made public since getters exist.

6. Added the View absolute coordinates in the screen to AccessibilityNodeInfo.
   This is needed for fast computation of relative positions of
   views from accessibility - common use case for the later.

7. Fixed a couple of marshalling bugs.

8. Added a test for the object contract of AccessibilityNodeInfo.

Change-Id: Id9dc50c33aff441e4c93d25ea316c9bbc4bd7a35
14 files changed