Restore Purchases complete event

Hi, I try to use Unity5 IAP: https://unity3d.com/ru/learn/tutorials/topics/analytics/integrating-unity-iap-your-game. How I can determine whether the restore purchases process is complete?

I read t$$anonymous$$s:

"On platforms that support it (e.g. Google Play and Universal Windows Applications) Unity IAP automatically restores any products the user owns during the first initialization following reinstallation; the ProcessPurchase method of your IStoreListener will be called for each owned item."

But in what way I can count owned items? I want have a normal callback on restore purchases complete event. Thank you for your time!