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

components/offline_pages/offline_page_metadata_store_sql.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_OFFLINE_PAGE_METADATA_STORE_SQL_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_SQL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 41 matching lines @@
 // * Upgrade should use |UpgradeWithQuery| and simply specify SQL command to
 //   move data from old table (prefixed by temp_) to the new one.
 class OfflinePageMetadataStoreSQL : public OfflinePageMetadataStore {
  public:
   OfflinePageMetadataStoreSQL(
       scoped_refptr<base::SequencedTaskRunner> background_task_runner,
       const base::FilePath& database_dir);
   ~OfflinePageMetadataStoreSQL() override;
 
   // Implementation methods.
+  void Initialize(const InitializeCallback& callback) override;
   void GetOfflinePages(const LoadCallback& callback) override;
   void AddOfflinePage(const OfflinePageItem& offline_page,
                       const AddCallback& callback) override;
   void UpdateOfflinePages(const std::vector<OfflinePageItem>& pages,
                           const UpdateCallback& callback) override;
   void RemoveOfflinePages(const std::vector<int64_t>& offline_ids,
                           const UpdateCallback& callback) override;
   void Reset(const ResetCallback& callback) override;
   StoreState state() const override;
 
   // Helper function used to force incorrect state for testing purposes.
   void SetStateForTesting(StoreState state, bool reset_db);
 
  private:
-  // Used to initialize DB connection.
-  void OpenConnection();
-  void OnOpenConnectionDone(StoreState state);
+  // Used to conclude opening/resetting DB connection.
+  void OnOpenConnectionDone(const InitializeCallback& callback, bool success);
+  void OnResetDone(const ResetCallback& callback, bool success);
 
-  // Used to reset DB connection.
-  void OnResetDone(const ResetCallback& callback, StoreState state);
-
-  // Helper function that checks whether a valid DB connection is present.
-  // Returns true if valid connection is present, otherwise it returns false and
-  // calls the provided callback as a shortcut.
-  bool CheckDb(const base::Closure& callback);
+  // Checks whether a valid DB connection is present and store state is LOADED.
+  bool CheckDb();
 
   // Background thread where all SQL access should be run.
   scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
 
   // Path to the database on disk.
   base::FilePath db_file_path_;
 
   // Database connection.
   std::unique_ptr<sql::Connection> db_;
 
   // State of the store.
   StoreState state_;
 
   base::WeakPtrFactory<OfflinePageMetadataStoreSQL> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageMetadataStoreSQL);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_SQL_H_