Make HTTP middleware easier to use

appengine/gaemiddleware/routes.go

Index: appengine/gaemiddleware/routes.go
diff --git a/appengine/gaemiddleware/routes.go b/appengine/gaemiddleware/routes.go
index e52cf252dff223198b99c65d8219e718aa4b9a4f..3de2caaa98ea681a56fda05ecbac17bf31af8e7b 100644
--- a/appengine/gaemiddleware/routes.go
+++ b/appengine/gaemiddleware/routes.go
@@ -5,8 +5,7 @@
 package gaemiddleware
 
 import (
-	"github.com/julienschmidt/httprouter"
-	"github.com/luci/luci-go/server/middleware"
+	"github.com/luci/luci-go/server/router"
 	"github.com/luci/luci-go/server/settings/admin"
 
 	gaeauth "github.com/luci/luci-go/appengine/gaeauth/server"
@@ -19,7 +18,7 @@ import (
 // work (e.g. authentication related routes, time series monitoring, etc).
 //
 // 'base' is expected to be BaseProd or its derivative.
-func InstallHandlers(r *httprouter.Router, base middleware.Base) {
+func InstallHandlers(r *router.Router, base router.MiddlewareChain) {
 	gaeauth.InstallWebHandlers(r, base)
 	tsmon.InstallHandlers(r, base)
 	admin.InstallHandlers(r, base, &gaeauth.UsersAPIAuthMethod{})