Create packages client/internal/ retry and lhttp.

client/internal/lhttp/utils.go

Index: client/internal/lhttp/utils.go
diff --git a/client/internal/lhttp/utils.go b/client/internal/lhttp/utils.go
new file mode 100644
index 0000000000000000000000000000000000000000..222d281d9bbbae94af66d64b05cf11a004f707de
--- /dev/null
+++ b/client/internal/lhttp/utils.go
@@ -0,0 +1,29 @@
+// 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 lhttp
+
+import (
+	"errors"
+	"net/url"
+	"strings"
+)
+
+// URLToHTTPS ensures the url is https://.
+func URLToHTTPS(s string) (string, error) {
+	u, err := url.Parse(s)
+	if err != nil {
+		return "", err
+	}
+	if u.Scheme != "" && u.Scheme != "https" {
+		return "", errors.New("Only https:// scheme is accepted. It can be omitted.")
+	}
+	if !strings.HasPrefix(s, "https://") {
+		s = "https://" + s
+	}
+	if _, err = url.Parse(s); err != nil {
+		return "", err
+	}
+	return s, nil
+}