Change gae to apache 2 license.

service/mail/testable.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
 
 // TestMessage is the message struct which will be returned from SentMessages.
 //
 // It augments the Message struct by also including the derived MIMEType for any
 // attachments.
 type TestMessage struct {
         Message
 
@@ skipping 23 matching lines @@
         // use ["admin@example.com"].
         SetAdminEmails(emails ...string)
 
         // SentMessages returns a copy of all messages which were successfully sent
         // via the mail API.
         SentMessages() []*TestMessage
 
         // Reset clears the SentMessages queue.
         Reset()
 }