Make HTTP middleware easier to use

appengine/cmd/dm/distributor/handlers.go

 // Copyright 2016 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 distributor
 
 import (
-        "net/http"
-
-        "github.com/julienschmidt/httprouter"
         "github.com/luci/luci-go/appengine/gaemiddleware"
-        "github.com/luci/luci-go/server/middleware"
-        "golang.org/x/net/context"
+        "github.com/luci/luci-go/server/router"
 )
 
 // InstallHandlers installs the taskqueue callback handler.
 //
 // The `base` middleware must have a registry installed with WithRegistry.
-func InstallHandlers(reg Registry, r *httprouter.Router, base middleware.Base) {
-        r.POST(handlerPattern, base(
-                gaemiddleware.RequireTaskQueue("", func(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
-                        TaskQueueHandler(WithRegistry(c, reg), rw, r, p)
-                })))
+func InstallHandlers(reg Registry, r *router.Router, base router.MiddlewareChain) {
+        r.POST(handlerPattern, append(base, gaemiddleware.RequireTaskQueue(""), func(c *router.Context, next router.Handler) {
+                c.Context = WithRegistry(c.Context, reg)
+                next(c)
+        }), TaskQueueHandler)
 
-        r.POST("/_ah/push-handlers/"+notifyTopicSuffix, base(
-                func(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
-                        PubsubReciever(WithRegistry(c, reg), rw, r, p)
-                }))
+        r.POST("/_ah/push-handlers/"+notifyTopicSuffix, append(base, func(c *router.Context, next router.Handler) {
+                c.Context = WithRegistry(c.Context, reg)
+                next(c)
+        }), PubsubReceiver)
 }