[Offline pages] Enabling notifications for pages saved later

components/offline_pages/downloads/download_notifying_observer.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_OFFLINE_PAGES_DOWNLOADS_DOWNLOAD_NOTIFYING_OBSERVER_H_
+#define COMPONENTS_OFFLINE_PAGES_DOWNLOADS_DOWNLOAD_NOTIFYING_OBSERVER_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "components/offline_pages/background/request_coordinator.h"
+
+namespace offline_pages {
+
+struct OfflinePageDownloadNotifier;
+class SavePageRequest;
+
+// Class observing the save page requests and issuing corresponding user
+// notifications as requests are added or updated.
+class DownloadNotifyingObserver : public RequestCoordinator::Observer,
+                                  public base::SupportsUserData::Data {
+ public:
+  ~DownloadNotifyingObserver() override;
+
+  static DownloadNotifyingObserver* GetFromRequestCoordinator(
+      RequestCoordinator* request_coordinator);
+  static void CreateAndStartObserving(
+      RequestCoordinator* request_coordinator,
+      std::unique_ptr<OfflinePageDownloadNotifier> notifier);
+
+  // RequestCoordinator::Observer implementation:
+  void OnAdded(const SavePageRequest& request) override;
+  void OnChanged(const SavePageRequest& request) override;
+  void OnCompleted(const SavePageRequest& request,
+                   RequestCoordinator::SavePageStatus status) override;
+
+ private:
+  friend class DownloadNotifyingObserverTest;
+
+  explicit DownloadNotifyingObserver(
+      std::unique_ptr<OfflinePageDownloadNotifier> notifier);
+
+  // Used to issue notifications related to save page requests.
+  std::unique_ptr<OfflinePageDownloadNotifier> notifier_;
+
+  DISALLOW_COPY_AND_ASSIGN(DownloadNotifyingObserver);
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_DOWNLOADS_DOWNLOAD_NOTIFYING_OBSERVER_H_