[Offline pages] Resetting offline page metadata store to handle LOAD/INIT failures

components/offline_pages/offline_page_metadata_store.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_METADATA_STORE_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 20 matching lines @@
   enum LoadStatus {
     LOAD_SUCCEEDED,
     STORE_INIT_FAILED,
     STORE_LOAD_FAILED,
     DATA_PARSING_FAILED,
 
     // NOTE: always keep this entry at the end.
     LOAD_STATUS_COUNT
   };
 
-  typedef base::Callback<void(LoadStatus, const std::vector<OfflinePageItem>&)>
+  typedef base::Callback<void(const std::vector<OfflinePageItem>&)>
       LoadCallback;
+  typedef base::Callback<void(bool)> InitializeCallback;
   typedef base::Callback<void(ItemActionStatus)> AddCallback;
   typedef base::Callback<void(std::unique_ptr<OfflinePagesUpdateResult>)>
       UpdateCallback;
   typedef base::Callback<void(bool)> ResetCallback;
 
   OfflinePageMetadataStore();
   virtual ~OfflinePageMetadataStore();
 
+  // Initializes the store. Should be called before any other methods.
+  virtual void Initialize(const InitializeCallback& callback) = 0;
+
   // Get all of the offline pages from the store.
   virtual void GetOfflinePages(const LoadCallback& callback) = 0;
 
   // Asynchronously adds an offline page item metadata to the store.
   virtual void AddOfflinePage(const OfflinePageItem& offline_page,
                               const AddCallback& callback) = 0;
 
   // Asynchronously updates a set of offline page items in the store.
   virtual void UpdateOfflinePages(const std::vector<OfflinePageItem>& pages,
                                   const UpdateCallback& callback) = 0;
 
   // Asynchronously removes offline page metadata from the store.
   // Result of the update is passed in callback.
   virtual void RemoveOfflinePages(const std::vector<int64_t>& offline_ids,
                                   const UpdateCallback& callback) = 0;
 
   // Resets the store.
   virtual void Reset(const ResetCallback& callback) = 0;
 
   // Gets the store state.
   virtual StoreState state() const = 0;
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_H_