Make HTTP middleware easier to use

appengine/cmd/helloworld_mvm/backend/main.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 // Package main implements HTTP server that handles requests to backend
 // module.
 package main
 
 import (
         "net/http"
 
-        "github.com/julienschmidt/httprouter"
-        "golang.org/x/net/context"
         "google.golang.org/appengine"
 
         "github.com/luci/luci-go/appengine/gaemiddleware"
-        "github.com/luci/luci-go/server/middleware"
+        "github.com/luci/luci-go/server/router"
 )
 
 // base is the root of the middleware chain.
-func base(h middleware.Handler) httprouter.Handle {
-        return gaemiddleware.BaseProd(h)
+func base() []router.Handler {
+        return gaemiddleware.BaseProd()
 }
 
 //// Routes.
 
 func main() {
-        router := httprouter.New()
-        gaemiddleware.InstallHandlers(router, base)
-        router.GET("/hi", base(sayHi))
+        router := router.New()
+        gaemiddleware.InstallHandlers(router, base())
+        router.GET("/hi", append(base(), sayHi)...)
         http.DefaultServeMux.Handle("/", router)
 
         appengine.Main()
 }
 
 //// Handlers.
 
-func sayHi(c context.Context, w http.ResponseWriter, r *http.Request, p httprouter.Params) {
-        w.Write([]byte("Hi, I'm backend"))
+func sayHi(c *router.Context) {
+        c.Writer.Write([]byte("Hi, I'm backend"))
 }