Add pause/resume functionality to precache

components/precache/core/precache_session_table.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_PRECACHE_CORE_PRECACHE_SESSION_TABLE_H_
+#define COMPONENTS_PRECACHE_CORE_PRECACHE_SESSION_TABLE_H_
+
+#include <list>
+#include <map>
+#include <memory>
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "url/gurl.h"
+
+namespace base {
+class TimeTicks;
+}
+
+namespace sql {
+class Connection;
+}
+
+namespace precache {
+
+class PrecacheUnfinishedWork;
+
+// Denotes the type of session information being stored.
+enum SessionDataType {
+  // Unfinished work to do sometime later.
+  UNFINISHED_WORK = 0,
+};
+
+class PrecacheSessionTable {
+ public:
+  PrecacheSessionTable();
+  virtual ~PrecacheSessionTable();
+
+  // Initializes the precache task URL table for use with the specified database
+  // connection. The caller keeps ownership of |db|, and |db| must not be null.
+  // Init must be called before any other methods.
+  bool Init(sql::Connection* db);
+
+  // Stores unfinished work.
+  void SaveUnfinishedWork(
+      std::unique_ptr<PrecacheUnfinishedWork> unfinished_work);
+
+  // Retrieves unfinished work.
+  std::unique_ptr<PrecacheUnfinishedWork> GetUnfinishedWork();
+
+  // Removes all unfinished work from the database.
+  void DeleteUnfinishedWork();
+
+ private:
+  bool CreateTableIfNonExistent();
+
+  // Non-owned pointer.
+  sql::Connection* db_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrecacheSessionTable);
+};
+
+}  // namespace precache
+#endif  // COMPONENTS_PRECACHE_CORE_PRECACHE_SESSION_TABLE_H_