initial add of SQL based storage

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>
+#include <vector>
+
+#include "base/files/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "components/offline_pages/offline_page_metadata_store.h"
+
+namespace sql {
+class Connection;
+class MetaTable;
+class Statement;
+class StatementID;
+}
+
+namespace base {
+class SequencedTaskRunner;
+}
+
+namespace offline_pages {
+
+// OfflinePageMetadataStoreSQL is an instance of OfflinePageMetadataStore
+// which is implemented using a SQLite database.
+class OfflinePageMetadataStoreSQL : public OfflinePageMetadataStore {
+ public:
+  OfflinePageMetadataStoreSQL(
+      scoped_refptr<base::SequencedTaskRunner> background_task_runner,
+      const base::FilePath& database_dir);
+  ~OfflinePageMetadataStoreSQL() override;
+
+  // Implementation methods.
+  void Load(const LoadCallback& callback) override;
+  void AddOrUpdateOfflinePage(const OfflinePageItem& offline_page,
+                              const UpdateCallback& callback) override;
+  void RemoveOfflinePages(const std::vector<int64_t>& offline_ids,
+                          const UpdateCallback& callback) override;
+  void Reset(const ResetCallback& callback) override;
+
+  // If true, use an in-memory database to make testing easier.
+  // Only has an effect if you call it before a call to Load(...).
+  // Should only be used for testing.
+  void SetInMemoryDatabaseForTesting(bool in_memory);
+
+ private:
+  bool InitDatabase();
+
+  // Synchronous implementations, these are run on the background thread
+  // and actually do the work to access SQL.  The implementations above
+  // simply dispatch to the corresponding *Sync method on the background thread.
+  // 'runner' is where to run the callback.
+  void LoadSync(scoped_refptr<base::SingleThreadTaskRunner> runner,
+                const LoadCallback& callback);
+  void AddOrUpdateOfflinePageSync(
+      const OfflinePageItem& offline_page,
+      scoped_refptr<base::SingleThreadTaskRunner> runner,
+      const UpdateCallback& callback);
+  void RemoveOfflinePagesSync(
+      const std::vector<int64_t>& offline_ids,
+      scoped_refptr<base::SingleThreadTaskRunner> runner,
+      const UpdateCallback& callback);
+  void ResetSync(scoped_refptr<base::SingleThreadTaskRunner> runner,
+                 const ResetCallback& callback);
+
+  void NotifyLoadResult(scoped_refptr<base::SingleThreadTaskRunner> runner,
+                        const LoadCallback& callback,
+                        LoadStatus status,
+                        const std::vector<OfflinePageItem>& result);
+
+  // 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_;
+
+  std::unique_ptr<sql::Connection> db_;
+
+  // only useful for testing.
+  bool use_in_memory_;
+
+  base::WeakPtrFactory<OfflinePageMetadataStoreSQL> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageMetadataStoreSQL);
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_SQL_H_