Add an API to Pause and Resume background offlining requests.

components/offline_pages/background/request_queue_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_BACKGROUND_REQUEST_QUEUE_STORE_SQL_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_STORE_SQL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 20 matching lines @@
       scoped_refptr<base::SequencedTaskRunner> background_task_runner,
       const base::FilePath& database_dir);
   ~RequestQueueStoreSQL() override;
 
   // RequestQueueStore implementation.
   void GetRequests(const GetRequestsCallback& callback) override;
   void AddOrUpdateRequest(const SavePageRequest& offline_page,
                           const UpdateCallback& callback) override;
   void RemoveRequests(const std::vector<int64_t>& request_ids,
                       const RemoveCallback& callback) override;
+  void ChangeRequestsState(const std::vector<int64_t>& request_ids,
+                           const SavePageRequest::RequestState new_state,
+                           const UpdateCallback& callback) override;
   void Reset(const ResetCallback& callback) override;
 
  private:
   // 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.
   static void GetRequestsSync(
       sql::Connection* db,
       scoped_refptr<base::SingleThreadTaskRunner> runner,
       const GetRequestsCallback& callback);
   static void AddOrUpdateRequestSync(
       sql::Connection* db,
       scoped_refptr<base::SingleThreadTaskRunner> runner,
       const SavePageRequest& offline_page,
       const UpdateCallback& callback);
   static void RemoveRequestsSync(
       sql::Connection* db,
       scoped_refptr<base::SingleThreadTaskRunner> runner,
       const std::vector<int64_t>& request_ids,
       const RemoveCallback& callback);
+  static void ChangeRequestsStateSync(
+      sql::Connection* db,
+      scoped_refptr<base::SingleThreadTaskRunner> runner,
+      const std::vector<int64_t>& request_ids,
+      const SavePageRequest::RequestState new_state,
+      const UpdateCallback& callback);
   static void ResetSync(sql::Connection* db,
                         const base::FilePath& db_file_path,
                         scoped_refptr<base::SingleThreadTaskRunner> runner,
                         const ResetCallback& callback);
 
+  // Helper functions to return immediately if no database is found.
+  bool CheckDb(const base::Closure& callback);
+
   // Used to initialize DB connection.
   static void OpenConnectionSync(
       sql::Connection* db,
       scoped_refptr<base::SingleThreadTaskRunner> runner,
       const base::FilePath& path,
       const base::Callback<void(bool)>& callback);
   void OpenConnection();
   void OnOpenConnectionDone(bool success);
 
   // Used to finalize connection reset.
   void OnResetDone(const ResetCallback& callback, bool success);
 
   // 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_;
 
   base::WeakPtrFactory<RequestQueueStoreSQL> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(RequestQueueStoreSQL);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_STORE_SQL_H_