How to call a www synchronously?

In 99% of cases, async is the way to go. However, upon OnApplicationQuit(), sync would be preferred:

For example, you know when you play League of Legends, they know you left a match, even if you close the app dirty? Something like that -- I wanted to make a short call to our API. Seems that anything async just causes the app to close before it's done (since it's like "last resort code" I suppose).

 

http://answers.unity3d.com/questions/465925/how-to-save-to-a-database-on-application-close.html

This answer is what you are looking for I believe, hope it helps.