Simplify handling of overlapped result

There is not necessary to pass direction to handleOverlappedResult().
Because it is passed already as a second argument (pointer to
OVERLAPPED structure that defines a desired direction).

Also this method is renamed to more simple and short name.

Change-Id: I9c20cf97c1712aed8d3e9ea6d9b4687ce4487523
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>