Move base64url.* to CryptAuth component.

components/proximity_auth/base64url.h

-// Copyright 2014 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_PROXIMITY_BASE64URL_H
-#define COMPONENTS_PROXIMITY_BASE64URL_H
-
-#include <string>
-
-namespace proximity_auth {
-
-// An implmentation of the base64url encoding. Escapes the unsafe '+' and '/'
-// characters with the url-safe alternatives '-' and '_', respectively. For more
-// info, see the section on "Base 64 Encoding with URL and Filename Safe
-// Alphabet" in http://www.ietf.org/rfc/rfc4648.txt
-// NOTE: Unlike many common web-safe encodings, this function does not escape
-// the '=' character. This is to match the expectations set by Android.
-// TODO(isherman): There are several (semantically slightly different)
-// implementations of this within the Chromium codebase. Try to unify them.
-void Base64UrlEncode(const std::string& decoded_input,
-                     std::string* encoded_output);
-
-// The inverse operation for the base64url encoding above.
-bool Base64UrlDecode(const std::string& encoded_input,
-                     std::string* decoded_output);
-
-}  // namespace proximity_auth
-
-#endif  // COMPONENTS_PROXIMITY_BASE64URL_H