AspNetCore.Docs/aspnet/whitepapers/aspnet4/overview/samples/sample34.cs

public class CustomProvider : HttpCapabilitiesEvaluator 
{ 
	public override HttpBrowserCapabilities 
	GetBrowserCapabilities(HttpRequest request) 
	{ 
		HttpBrowserCapabilities browserCaps = 
		  base.GetHttpBrowserCapabilities(request); 
		if (browserCaps.Browser == "Unknown") 
		{ 
			browserCaps = MyBrowserCapabilitiesEvaulator(request); 
		} 
		return browserCaps; 
	}
}