The message processing may finish before watcherHelper is
setup. Use locking and an additional check for message
processing completion to avoid the race condition.
Move the code to new function inside QDBusPendingCallPrivate,
close to where the waiting without GUI is done.
Add assertions that check that watcherHelper is not overwritten.
Change-Id: I24e54598135edf293c41b3a80369b0a3b46f775c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>