Change gae to apache 2 license.

service/mail/context.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.
+// 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 mail
 
 import (
         "golang.org/x/net/context"
 )
 
 type key int
 
 var (
@@ skipping 57 matching lines @@
 func AddFilters(c context.Context, filts ...Filter) context.Context {
         if len(filts) == 0 {
                 return c
         }
         cur := getCurFilters(c)
         newFilts := make([]Filter, 0, len(cur)+len(filts))
         newFilts = append(newFilts, getCurFilters(c)...)
         newFilts = append(newFilts, filts...)
         return context.WithValue(c, serviceFilterKey, newFilts)
 }