Settings reset prompt: Add a test for the default settings fetcher.

chrome/browser/safe_browsing/settings_reset_prompt/default_settings_fetcher.h

+// Copyright 2017 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 CHROME_BROWSER_SAFE_BROWSING_SETTINGS_RESET_PROMPT_DEFAULT_SETTINGS_FETCHER_H_
+#define CHROME_BROWSER_SAFE_BROWSING_SETTINGS_RESET_PROMPT_DEFAULT_SETTINGS_FETCHER_H_
+
+#include <memory>
+
+#include "base/callback.h"
+
+class BrandcodedDefaultSettings;
+class BrandcodeConfigFetcher;
+
+namespace safe_browsing {
+
+// Class that fetches default settings to be used for the settings reset
+// prompt. The static |FetchDefaultSettings()| function will create and manage
+// the lifetime of |DefaultSettingsFetcher| instances.
+class DefaultSettingsFetcher {
+ public:
+  using SettingsCallback =
+      base::Callback<void(std::unique_ptr<BrandcodedDefaultSettings>)>;
+
+  // Fetches default settings and passes the corresponding
+  // |BrandcodedDefaultSettings| object to |callback| on the UI thread. The

[csharp, 2017/05/01 19:11:37]

nit: The function -> This function (I think it makes it a bit clearer)

Also, should be -> must be?

[alito, 2017/05/01 19:18:19]

Done.

+  // function should be called on the UI thread as well.
+  static void FetchDefaultSettings(SettingsCallback callback);
+  // Allows tests to specify the default settings that were fetched in
+  // |fetched_settings|. Passing nullptr as |fetched_settings| corresponds to
+  // the case when fetching default settings over the network fails.
+  static void FetchDefaultSettingsForTesting(
+      SettingsCallback callback,
+      std::unique_ptr<BrandcodedDefaultSettings> fetched_settings);
+
+ private:
+  // Instances of |DefaultSettingsFetcher| own themselves and will delete
+  // themselves once default settings have been fetched and |callback| has been
+  // posted on the UI thread.
+  //
+  // The main reason for this design is that |BrandcodeConfigFetcher| takes a
+  // callback and initiates the fetching process in its constructor, and we need
+  // to hold on to the instance of the fetcher until settings have been
+  // fetched. This design saves us from having to explicitly manage global
+  // |BrandcodeConfigFetcher| instances.
+  explicit DefaultSettingsFetcher(SettingsCallback callback);
+  ~DefaultSettingsFetcher();
+
+  // Starts the process of fetching default settings and will ensure that
+  // |PostCallbackAndDeleteSelf| is called once settings have been fetched.
+  void Start();
+  void OnSettingsFetched();
+  // Posts a call to |callback_| on the UI thread, passing to it
+  // |default_settings|, and deletes |this|.
+  void PostCallbackAndDeleteSelf(
+      std::unique_ptr<BrandcodedDefaultSettings> default_settings);
+
+  std::unique_ptr<BrandcodeConfigFetcher> config_fetcher_;
+  SettingsCallback callback_;
+};
+
+}  // namespace safe_browsing
+
+#endif  // CHROME_BROWSER_SAFE_BROWSING_SETTINGS_RESET_PROMPT_DEFAULT_SETTINGS_FETCHER_H_