[Session restore] Add MRU logic to loading of background pages.

components/sessions/session_service_commands.h

 // Copyright 2014 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_SERVICE_COMMANDS_H_
 #define COMPONENTS_SESSIONS_SESSION_SERVICE_COMMANDS_H_
 
 #include <map>
 #include <string>
 
@@ skipping 60 matching lines @@
     const sessions::SerializedNavigationEntry& navigation);
 SESSIONS_EXPORT scoped_ptr<SessionCommand> CreateSetTabExtensionAppIDCommand(
     const SessionID& tab_id,
     const std::string& extension_id);
 SESSIONS_EXPORT scoped_ptr<SessionCommand> CreateSetTabUserAgentOverrideCommand(
     const SessionID& tab_id,
     const std::string& user_agent_override);
 SESSIONS_EXPORT scoped_ptr<SessionCommand> CreateSetWindowAppNameCommand(
     const SessionID& window_id,
     const std::string& app_name);
+SESSIONS_EXPORT scoped_ptr<SessionCommand> CreateActivationTimeCommand(
+    const SessionID& tab_id,
+    base::TimeTicks activation_time);
 
 // Searches for a pending command using |base_session_service| that can be
 // replaced with |command|. If one is found, pending command is removed, the
 // command is added to the pending commands (taken ownership) and true is
 // returned.
 SESSIONS_EXPORT bool ReplacePendingCommand(
     BaseSessionService* base_session_service,
     scoped_ptr<SessionCommand>* command);
 
 // Returns true if provided |command| either closes a window or a tab.
 SESSIONS_EXPORT bool IsClosingCommand(SessionCommand* command);
 
 // Converts a list of commands into SessionWindows. On return any valid
 // windows are added to valid_windows. It is up to the caller to delete
 // the windows added to valid_windows. |active_window_id| will be set with the
 // id of the last active window, but it's only valid when this id corresponds
 // to the id of one of the windows in valid_windows.
 SESSIONS_EXPORT void RestoreSessionFromCommands(
     const ScopedVector<SessionCommand>& commands,
     std::vector<SessionWindow*>* valid_windows,
     SessionID::id_type* active_window_id);
 
 }  // namespace sessions
 
 #endif  // COMPONENTS_SESSIONS_SESSION_SERVICE_COMMANDS_H_