[Offline pages] Adapting OfflinePageDownloadBridge to DownloadUIAdapter

components/offline_pages/downloads/download_ui_adapter.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_PAGE_DOWNLOADS_DOWNLOAD_UI_ADAPTER_H_
 #define COMPONENTS_OFFLINE_PAGE_DOWNLOADS_DOWNLOAD_UI_ADAPTER_H_
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/observer_list.h"
+#include "base/supports_user_data.h"
 #include "components/offline_pages/downloads/download_ui_item.h"
 #include "components/offline_pages/offline_page_model.h"
 #include "components/offline_pages/offline_page_types.h"
 
 namespace offline_pages {
 
 // Key is DownloadUIItem.guid.
 typedef
     std::map<std::string, std::unique_ptr<DownloadUIItem>> DownloadUIItemsMap;
 
 // C++ side of the UI Adapter. Mimics DownloadManager/Item/History (since we
 // share UI with Downloads).
 // An instance of this class is owned by OfflinePageModel and is shared between
 // UI components if needed. It manages the cache of DownloadUIItems, so after
 // initial load the UI components can synchronously pull the whoel list or any
 // item by its guid.
-class DownloadUIAdapter : public OfflinePageModel::Observer {
+class DownloadUIAdapter : public OfflinePageModel::Observer,
+                          public base::SupportsUserData::Data {
  public:
   // Observer, normally implemented by UI or a Bridge.
   class Observer {
    public:
     // Invoked when UI items are loaded. GetAllItems/GetItem can now be used.
     // Must be listened for in order to start getting the items.
     // If the items are already loaded by the time observer is added, this
     // callback will be posted right away.
     virtual void ItemsLoaded() = 0;
 
     // Invoked when the UI Item was added, usually as a request to download.
     virtual void ItemAdded(const DownloadUIItem& item) = 0;
 
     // Invoked when the UI Item was updated. Only guid of the item is guaranteed
     // to survive the update, all other fields can change.
     virtual void ItemUpdated(const DownloadUIItem& item) = 0;
 
     // Invoked when the UI Item was deleted. At this point, only guid remains.
     virtual void ItemDeleted(const std::string& guid) = 0;
 
    protected:
     virtual ~Observer() = default;
   };
 
   explicit DownloadUIAdapter(OfflinePageModel* model);
   ~DownloadUIAdapter() override;
 
+  static DownloadUIAdapter* FromOfflinePageModel(
+      OfflinePageModel* offline_page_model);
+
   // This adapter is potentially shared by UI elements, each of which adds
   // itself as an observer.
   // When the last observer si removed, cached list of items is destroyed and
   // next time the initial loading will take longer.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
   const DownloadUIItemsMap& GetAllItems() const;
   // May return nullptr.
   const DownloadUIItem* GetItem(const std::string& guid) const;
@@ skipping 25 matching lines @@
   // The observers.
   base::ObserverList<Observer> observers_;
 
   base::WeakPtrFactory<DownloadUIAdapter> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadUIAdapter);
 };
 
 }  // namespace offline_pages
 
-#endif  // COMPONENTS_OFFLINE_PAGE_DOWNLOADS_DOWNLOAD_UI_ADAPTER_H_
+#endif  // COMPONENTS_OFFLINE_PAGE_DOWNLOADS_DOWNLOAD_UI_ADAPTER_H_