Local NTP: Introduce OneGoogleBarService

chrome/browser/search/one_google_bar/one_google_bar_service.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_SEARCH_ONE_GOOGLE_BAR_ONE_GOOGLE_BAR_SERVICE_H_
+#define CHROME_BROWSER_SEARCH_ONE_GOOGLE_BAR_ONE_GOOGLE_BAR_SERVICE_H_
+
+#include <memory>
+
+#include "base/observer_list.h"
+#include "base/optional.h"
+#include "chrome/browser/search/one_google_bar/one_google_bar_data.h"
+#include "chrome/browser/search/one_google_bar/one_google_bar_service_observer.h"
+#include "components/keyed_service/core/keyed_service.h"
+
+class OneGoogleBarFetcher;
+class SigninManagerBase;
+
+// A service that downloads, caches, and hands out OneGoogleBarData. It never
+// initiates a download automatically, only when Refresh is called. When the
+// user signs in or out, the cached value is cleared.
+class OneGoogleBarService : public KeyedService {
+ public:
+  OneGoogleBarService(SigninManagerBase* signin_manager,
+                      std::unique_ptr<OneGoogleBarFetcher> fetcher);
+  ~OneGoogleBarService() override;
+
+  // KeyedService implementation.
+  void Shutdown() override;
+
+  // Returns the currently cached OneGoogleBarData, if any.
+  const base::Optional<OneGoogleBarData>& one_google_bar_data() const {
+    return one_google_bar_data_;
+  }
+
+  // Requests an asynchronous refresh from the network. After the update
+  // completes, the observers will be notified only if something changed.
+  void Refresh();
+
+  // Add/remove observers. All observers must unregister themselves before the
+  // OneGoogleBarService is destroyed.
+  void AddObserver(OneGoogleBarServiceObserver* observer);
+  void RemoveObserver(OneGoogleBarServiceObserver* observer);
+
+ private:
+  class SigninObserver;
+
+  void SigninStatusChanged();
+
+  void SetOneGoogleBarData(const base::Optional<OneGoogleBarData>& data);
+
+  std::unique_ptr<OneGoogleBarFetcher> fetcher_;
+
+  std::unique_ptr<SigninObserver> signin_observer_;
+
+  base::ObserverList<OneGoogleBarServiceObserver, true> observers_;
+
+  base::Optional<OneGoogleBarData> one_google_bar_data_;
+};
+
+#endif  // CHROME_BROWSER_SEARCH_ONE_GOOGLE_BAR_ONE_GOOGLE_BAR_SERVICE_H_