Move all core files in //components/sessions into core/ subdir

components/sessions/session_backend.h

-// Copyright 2011 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_SESSIONS_SESSION_BACKEND_H_
-#define COMPONENTS_SESSIONS_SESSION_BACKEND_H_
-
-#include <vector>
-
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/task/cancelable_task_tracker.h"
-#include "components/sessions/base_session_service.h"
-#include "components/sessions/session_command.h"
-#include "components/sessions/sessions_export.h"
-
-namespace base {
-class File;
-}
-
-namespace sessions {
-// SessionBackend -------------------------------------------------------------
-
-// SessionBackend is the backend used by BaseSessionService. It is responsible
-// for maintaining two files:
-// . The current file, which is the file commands passed to AppendCommands
-//   get written to.
-// . The last file. When created the current file is moved to the last
-//   file.
-//
-// Each file contains an arbitrary set of commands supplied from
-// BaseSessionService. A command consists of a unique id and a stream of bytes.
-// SessionBackend does not use the id in anyway, that is used by
-// BaseSessionService.
-class SESSIONS_EXPORT SessionBackend
-    : public base::RefCountedThreadSafe<SessionBackend> {
- public:
-  typedef sessions::SessionCommand::id_type id_type;
-  typedef sessions::SessionCommand::size_type size_type;
-
-  // Initial size of the buffer used in reading the file. This is exposed
-  // for testing.
-  static const int kFileReadBufferSize;
-
-  // Creates a SessionBackend. This method is invoked on the MAIN thread,
-  // and does no IO. The real work is done from Init, which is invoked on
-  // the file thread.
-  //
-  // |path_to_dir| gives the path the files are written two, and |type|
-  // indicates which service is using this backend. |type| is used to determine
-  // the name of the files to use as well as for logging.
-  SessionBackend(sessions::BaseSessionService::SessionType type,
-                 const base::FilePath& path_to_dir);
-
-  // Moves the current file to the last file, and recreates the current file.
-  //
-  // NOTE: this is invoked before every command, and does nothing if we've
-  // already Init'ed.
-  void Init();
-  bool inited() const { return inited_; }
-
-  // Appends the specified commands to the current file. If reset_first is
-  // true the the current file is recreated.
-  void AppendCommands(ScopedVector<sessions::SessionCommand> commands,
-                      bool reset_first);
-
-  // Invoked from the service to read the commands that make up the last
-  // session, invokes ReadLastSessionCommandsImpl to do the work.
-  void ReadLastSessionCommands(
-      const base::CancelableTaskTracker::IsCanceledCallback& is_canceled,
-      const sessions::BaseSessionService::GetCommandsCallback& callback);
-
-  // Reads the commands from the last file.
-  //
-  // On success, the read commands are added to commands.
-  bool ReadLastSessionCommandsImpl(
-      ScopedVector<sessions::SessionCommand>* commands);
-
-  // Deletes the file containing the commands for the last session.
-  void DeleteLastSession();
-
-  // Moves the current session to the last and resets the current. This is
-  // called during startup and if the user launchs the app and no tabbed
-  // browsers are running.
-  void MoveCurrentSessionToLastSession();
-
-  // Reads the commands from the current file.
-  //
-  // On success, the read commands are added to commands. It is up to the
-  // caller to delete the commands.
-  bool ReadCurrentSessionCommandsImpl(
-      ScopedVector<sessions::SessionCommand>* commands);
-
- private:
-  friend class base::RefCountedThreadSafe<SessionBackend>;
-
-  ~SessionBackend();
-
-  // If current_session_file_ is open, it is truncated so that it is essentially
-  // empty (only contains the header). If current_session_file_ isn't open, it
-  // is is opened and the header is written to it. After this
-  // current_session_file_ contains no commands.
-  // NOTE: current_session_file_ may be NULL if the file couldn't be opened or
-  // the header couldn't be written.
-  void ResetFile();
-
-  // Opens the current file and writes the header. On success a handle to
-  // the file is returned.
-  base::File* OpenAndWriteHeader(const base::FilePath& path);
-
-  // Appends the specified commands to the specified file.
-  bool AppendCommandsToFile(
-      base::File* file,
-      const ScopedVector<sessions::SessionCommand>& commands);
-
-  const sessions::BaseSessionService::SessionType type_;
-
-  // Returns the path to the last file.
-  base::FilePath GetLastSessionPath();
-
-  // Returns the path to the current file.
-  base::FilePath GetCurrentSessionPath();
-
-  // Directory files are relative to.
-  const base::FilePath path_to_dir_;
-
-  // Whether the previous target file is valid.
-  bool last_session_valid_;
-
-  // Handle to the target file.
-  scoped_ptr<base::File> current_session_file_;
-
-  // Whether we've inited. Remember, the constructor is run on the
-  // Main thread, all others on the IO thread, hence lazy initialization.
-  bool inited_;
-
-  // If true, the file is empty (no commands have been added to it).
-  bool empty_file_;
-
-  DISALLOW_COPY_AND_ASSIGN(SessionBackend);
-};
-
-}  // namespace sessions
-
-#endif  // COMPONENTS_SESSIONS_SESSION_BACKEND_H_