amazon: add amazon endpoints

Change-Id: Ib34eee690295615576ea6b0a5a17fa4ecde0ce01
Reviewed-on: https://go-review.googlesource.com/40402
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

amazon/amazon.go

@@ -0,0 +1,16 @@
+// Copyright 2017 The oauth2 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 amazon provides constants for using OAuth2 to access Amazon.
+package amazon
+
+import (
+	"golang.org/x/oauth2"
+)
+
+// Endpoint is Amazon's OAuth 2.0 endpoint.
+var Endpoint = oauth2.Endpoint{
+	AuthURL:  "https://www.amazon.com/ap/oa",
+	TokenURL: "https://api.amazon.com/auth/o2/token",
+}