Add filters for user service.

filter/featureBreaker/user.go

Index: filter/featureBreaker/user.go
diff --git a/filter/featureBreaker/user.go b/filter/featureBreaker/user.go
new file mode 100644
index 0000000000000000000000000000000000000000..af409a0bd4fa2762f09a351584ff31683ec40e9c
--- /dev/null
+++ b/filter/featureBreaker/user.go
@@ -0,0 +1,66 @@
+// 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 featureBreaker
+
+import (
+	"github.com/luci/gae/service/user"
+	"golang.org/x/net/context"
+)
+
+type userState struct {
+	*state
+
+	user.Interface
+}
+
+var _ user.Interface = (*userState)(nil)
+
+func (u *userState) CurrentOAuth(scopes ...string) (ret *user.User, err error) {
+	err = u.run(func() (err error) {
+		ret, err = u.Interface.CurrentOAuth(scopes...)
+		return
+	})
+	return
+}
+
+func (u *userState) LoginURL(dest string) (ret string, err error) {
+	err = u.run(func() (err error) {
+		ret, err = u.Interface.LoginURL(dest)
+		return
+	})
+	return
+}
+
+func (u *userState) LoginURLFederated(dest, identity string) (ret string, err error) {
+	err = u.run(func() (err error) {
+		ret, err = u.Interface.LoginURLFederated(dest, identity)
+		return
+	})
+	return
+}
+
+func (u *userState) LogoutURL(dest string) (ret string, err error) {
+	err = u.run(func() (err error) {
+		ret, err = u.Interface.LogoutURL(dest)
+		return
+	})
+	return
+}
+
+func (u *userState) OAuthConsumerKey() (ret string, err error) {
+	err = u.run(func() (err error) {
+		ret, err = u.Interface.OAuthConsumerKey()
+		return
+	})
+	return
+}
+
+// FilterUser installs a counter user filter in the context.
+func FilterUser(c context.Context, defaultError error) (context.Context, FeatureBreaker) {
+	state := newState(defaultError)
+	return user.AddFilters(c, func(ic context.Context, i user.Interface) user.Interface {
+		return &userState{state, i}
+	}), state
+}