[Offline pages] Resetting offline page metadata store if initial load fails

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>
 
 #include "base/callback.h"
 #include "components/offline_pages/offline_page_item.h"
 #include "components/offline_pages/offline_store_types.h"
 
 class GURL;
 
 namespace offline_pages {
 
 typedef StoreUpdateResult<OfflinePageItem> OfflinePagesUpdateResult;
 
 // OfflinePageMetadataStore keeps metadata for the offline pages.
 // Ability to create multiple instances of the store as well as behavior of
 // asynchronous operations when the object is being destroyed, before such
 // operation finishes will depend on implementation. It should be possible to
 // issue multiple asynchronous operations in parallel.
 class OfflinePageMetadataStore {
  public:
-  // This enum is used in an UMA histogram. Hence the entries here shouldn't
-  // be deleted or re-ordered and new ones should be added to the end.
-  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>&)>
-      LoadCallback;
+  typedef base::Callback<void(StoreState, const std::vector<OfflinePageItem>&)>
+      GetOfflinePagesCallback;
   typedef base::Callback<void(ItemActionStatus)> AddCallback;
   typedef base::Callback<void(std::unique_ptr<OfflinePagesUpdateResult>)>
       UpdateCallback;
   typedef base::Callback<void(bool)> ResetCallback;
 
   OfflinePageMetadataStore();
   virtual ~OfflinePageMetadataStore();
 
   // Get all of the offline pages from the store.
-  virtual void GetOfflinePages(const LoadCallback& callback) = 0;
+  virtual void GetOfflinePages(const GetOfflinePagesCallback& 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_