Make sure stateAboutToBeChanged(), stateChanged() is always called
from the debugger thread. This matches how messageReceived()
is called. On exit, run an event loop until all stateAboutToBeChanged
calls have returned.

Change-Id: I9cd6199cc80552ad97e4b7d504ea91aa116a6a34
Reviewed-by: Aurindam Jana <aurindam.jana@nokia.com>