Add custom webapi route

gistfile1.cs

using System.Linq;
using System.Web.Http;
using System.Web.Mvc;
using System.Web.Routing;
using Umbraco.Core;

namespace MyNamespace
{
    public class MyApplicationEventHandler : ApplicationEventHandler
    {
        protected override void ApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
            RouteTable.Routes.MapHttpRoute(
                "MyCustomApiRoute",
                "MyCustomApi/{controller}/{id}", new { id = UrlParameter.Optional });     
        }
    }
}

Wondering if this also would solve our recent trouble where we have a rewrite rule in web.config to force all backoffice (localhost/umbraco/) calls use https://(localhost/umbraco/), but that's causing cross-domain errors in our custom Surface controllers (/umbraco/surface/GetProducts/) where we're trying to return JSON data. (We get "No 'Access-Control-Allow-Origin' header" errors from JSON because it's trying to cross domains between http: and https:.