Make HTTP middleware easier to use

appengine/cmd/milo/settings/settings.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 settings
 
 import (
         "encoding/base64"
         "encoding/json"
         "fmt"
         "net/http"
 
-        "github.com/julienschmidt/httprouter"
         "github.com/luci/gae/service/datastore"
         "github.com/luci/luci-go/appengine/cmd/milo/model"
         "github.com/luci/luci-go/appengine/cmd/milo/resp"
         "github.com/luci/luci-go/server/auth"
         "github.com/luci/luci-go/server/auth/identity"
         "github.com/luci/luci-go/server/auth/xsrf"
+        "github.com/luci/luci-go/server/router"
         "golang.org/x/net/context"
 )
 
 type updateReq struct {
         Theme string
 }
 
 // GetTheme returns the chosen theme based on the current user.
 func GetTheme(c context.Context, r *http.Request) Theme {
         cfg := getUserSettings(c)
@@ skipping 38 matching lines @@
         }
         err = json.Unmarshal([]byte(s), &config)
         if err != nil {
                 panic(err)
         }
         return &config
 }
 
 // ChangeSettings is invoked in a POST request to settings and changes either
 // the user settings in the datastore, or the cookies if user is anon.
-func ChangeSettings(c context.Context, h http.ResponseWriter, r *http.Request, p httprouter.Params) {
+func ChangeSettings(ctx *router.Context) {
+        c, h, r := ctx.Context, ctx.Writer, ctx.Request
+
         // First, check XSRF token.
         err := xsrf.Check(c, r.FormValue("xsrf_token"))
         if err != nil {
                 h.WriteHeader(http.StatusUnauthorized)
                 h.Write([]byte("Failed XSRF check."))
                 return
         }
 
         u := &updateReq{
                 Theme: r.FormValue("theme"),
@@ skipping 52 matching lines @@
 
         result := &resp.Settings{}
         result.ActionURL = r.URL.String()
         result.Theme = &resp.Choices{
                 Choices:  GetAllThemes(),
                 Selected: userSettings.Theme,
         }
 
         return result, nil
 }