[rac] Temporarily copy libaddressinput to Chrome.

third_party/libaddressinput/chromium/cpp/include/libaddressinput/downloader.h

+// Copyright (C) 2013 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// The interface to be implemented by the user of the library to enable
+// downloading validation rules from a server.
+
+#ifndef I18N_ADDRESSINPUT_DOWNLOADER_H_
+#define I18N_ADDRESSINPUT_DOWNLOADER_H_
+
+#include <libaddressinput/callback.h>
+
+#include <string>
+
+namespace i18n {
+namespace addressinput {
+
+// Downloads validation rules from the server. Sample usage:
+//    class MyDownloader : public Downloader {
+//     public:
+//      virtual void Download(const std::string& url,
+//                            const Callback& downloaded) const {
+//        bool success = ...
+//        std::string data = ...
+//        downloaded(success, url, data);
+//      }
+//    };
+class Downloader {
+ public:
+  typedef i18n::addressinput::Callback<std::string, std::string> Callback;
+
+  virtual ~Downloader() {}
+
+  // Downloads |url| and invokes the |downloaded| callback.
+  virtual void Download(const std::string& url,
+                        const Callback& downloaded) const = 0;
+};
+
+}  // namespace addressinput
+}  // namespace i18n
+
+#endif  // I18N_ADDRESSINPUT_DOWNLOADER_H_