Adds a base32 component.

components/base32/base32.h

+// Copyright 2016 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.
+
+#ifndef COMPONENTS_BASE32_BASE32_H_
+#define COMPONENTS_BASE32_BASE32_H_
+
+#include <string>
+
+#include "base/strings/string_piece.h"
+
+namespace base32 {
+
+enum class Base32EncodePolicy {
+  // Include the trailing padding in the output, when necessary.
+  INCLUDE_PADDING,
+  // Remove the trailing padding from the output.

[gab, 2016/06/03 18:46:11]

// Omit trailing padding to the output. Such an output will not be decodable but
its size is guaranteed to be |max(8, ceil(input.size() * 8.0 / 5.0))|.

[Rob Percival, 2016/06/04 06:20:25]

That isn't quite accurate. It is decodable, if you know what size the input was
(in fact, I'm counting on that for my use of this encoder). Also, in the case of
|input| being empty, the output will also be empty (so it does not have a
minimum size of 8 bytes as stated). Is there much value to stating what the size
will be anyway?

By the way, should I update base/base64url.h as well? This enum was more or less
copy-and-pasted from there.

[gab, 2016/06/07 01:24:10]

Your latest version lg to me.
If you want to but I don't feel strongly.

+  OMIT_PADDING
+};
+
+// Encodes the |input| string in base32, defined in RFC 4648:
+// https://tools.ietf.org/html/rfc4648#section-5
+//
+// The |policy| defines whether padding should be included or omitted from the
+// encoded output.
+std::string Base32Encode(
+    base::StringPiece input,
+    Base32EncodePolicy policy = Base32EncodePolicy::INCLUDE_PADDING);
+
+}  // namespace base32
+
+#endif  // COMPONENTS_BASE32_BASE32_H_