Inter process interrogation ocassionally gets stuck.

1. There was a bug that was not handling correctly the
   case for which the interrogator requests an accessibility
   node info and the message describing how to fetch the
   latter for the same process case was delivered after the
   code that checks whether the message is there in order to
   dispatch it is executed. Now the message handling is done
   correctly - the caller checks if the message is present and
   if so processes it, otherwise the caller sleeps and is
   interrupted if such a message arrives.

bug:5138933

Change-Id: I4c2940b46c9a52a51c5ee48b83ca6811489765d6