如何在golang中获取HTTP请求的初始时间戳？

I am writing a golang program using revel framework, in which i need to check the initial timestamp of a http request.

I know how to do it in C# :

 HttpContextWrapper context = Request.Properties["MS_HttpContext"] as HttpContextWrapper;

DateTime t2 = context.Timestamp.ToUniversalTime();

Didn't get much how to do it in Go.