[Offline] Creates metadata store interface for offline pages

components/offline_pages/offline_page_model.h

 // Copyright 2015 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_OFFLINE_PAGE_MODEL_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_
 
 #include <vector>
 
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "components/keyed_service/core/keyed_service.h"
 
 class GURL;
 
 namespace offline_pages {
 
 struct OfflinePageItem;
+class OfflinePageMetadataStore;
 
 // Serivce for saving pages offline, storing the offline copy and metadata, and
 // retrieving them upon request.
 class OfflinePageModel : public KeyedService {
  public:
-  OfflinePageModel();
+  explicit OfflinePageModel(scoped_ptr<OfflinePageMetadataStore> store);
   ~OfflinePageModel() override;
 
   // KeyedService:
   void Shutdown() override;
 
   // Saves the page loaded in the web contents offline.
   void SavePageOffline(const GURL& url);
 
   // Gets a set of all offline pages metadata.
   std::vector<OfflinePageItem> GetAllOfflinePages();
 
+  // Methods for testing only:
+  OfflinePageMetadataStore* GetStoreForTesting();
+
  private:
+  // Persistent store for offline page metadata.
+  scoped_ptr<OfflinePageMetadataStore> store_;
+
   DISALLOW_COPY_AND_ASSIGN(OfflinePageModel);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_