Add a MustNamespace that panics if the namespace wasn't valid

filter/count/gi.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package count
 
 import (
         "time"
 
         "golang.org/x/net/context"
@@ skipping 12 matching lines @@
         IsDevAppServer         Entry
         IsOverQuota            Entry
         IsTimeoutError         Entry
         ModuleHostname         Entry
         ModuleName             Entry
         RequestID              Entry
         ServerSoftware         Entry
         ServiceAccount         Entry
         VersionID              Entry
         Namespace              Entry
+        MustNamespace          Entry
         AccessToken            Entry
         PublicCertificates     Entry
         SignBytes              Entry
 }
 
 type infoCounter struct {
         c *InfoCounter
 
         gi info.Interface
 }
@@ skipping 73 matching lines @@
 func (g *infoCounter) VersionID() string {
         _ = g.c.VersionID.up()
         return g.gi.VersionID()
 }
 
 func (g *infoCounter) Namespace(namespace string) (context.Context, error) {
         ret, err := g.gi.Namespace(namespace)
         return ret, g.c.Namespace.up(err)
 }
 
+func (g *infoCounter) MustNamespace(namespace string) context.Context {
+        g.c.MustNamespace.up()
+        return g.gi.MustNamespace(namespace)
+}
+
 func (g *infoCounter) AccessToken(scopes ...string) (string, time.Time, error) {
         token, expiry, err := g.gi.AccessToken(scopes...)
         return token, expiry, g.c.AccessToken.up(err)
 }
 
 func (g *infoCounter) PublicCertificates() ([]info.Certificate, error) {
         ret, err := g.gi.PublicCertificates()
         return ret, g.c.PublicCertificates.up(err)
 }
 
 func (g *infoCounter) SignBytes(bytes []byte) (string, []byte, error) {
         keyName, signature, err := g.gi.SignBytes(bytes)
         return keyName, signature, g.c.SignBytes.up(err)
 }
 
 // FilterGI installs a counter GlobalInfo filter in the context.
 func FilterGI(c context.Context) (context.Context, *InfoCounter) {
         state := &InfoCounter{}
         return info.AddFilters(c, func(ic context.Context, gi info.Interface) info.Interface {
                 return &infoCounter{state, gi}
         }), state
 }