Fix chrome_FileThread crash on windows

The file thread won't do anyting if it uses the Qt event loop therefore
it won't quit properly and this behavior leads to a crash.
Thus the chromium's IO message loop should be used on Windows too.

Change-Id: Ieea0ceb8bd732ed6c9ca172620511d78b0a5d95c
Reviewed-by: Andras Becsi <andras.becsi@digia.com>