Google map apis in unity (Directions,marker,...)

I have spent a week to find some way to use google map apis in unity. The one i want to use is directions api, marker and many other api. But i only find javascipt code, i cant find any in c# or unity tutorial,except this one: "https://www.youtube.com/watch?v=3ExhMNLmQtc"

The api have an url which will return to json but i dont know how to use that data to display the direction line in unity, (there is any library for it?) .Can someone tell me or give me some source about it, thank you.My destination is make a app have some feature like google map app.