Implement Mail service.

service/mail/interface.go

Index: service/mail/interface.go
diff --git a/service/mail/interface.go b/service/mail/interface.go
new file mode 100644
index 0000000000000000000000000000000000000000..cb949800f4d66a7b741383d9bd11f6bae23a7e7f
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+++ b/service/mail/interface.go
@@ -0,0 +1,13 @@
+// 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 mail
+
+// Interface is the interface for all of the mail methods.
+type Interface interface {
+	Send(msg *Message) error
+	SendToAdmins(msg *Message) error

[martiniss, 2015/12/16 21:54:15]

Why is this a separate function? Also, do these need to be documented? 

[iannucci, 2015/12/17 00:01:07]

These are the same as the functions in the SDK. I'll mention that in the
interface doc string, but I don't want to copy-paste documentation (that said,
the upstream docs are pretty bad too...)

+
+	Testable() Testable
+}