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

components/sessions/session_types.h

 // Copyright 2012 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_TYPES_H_
 #define COMPONENTS_SESSIONS_SESSION_TYPES_H_
 
 #include <algorithm>
 #include <string>
 #include <vector>
@@ skipping 79 matching lines @@
   // If non-empty, this tab is an app tab and this is the id of the extension.
   std::string extension_app_id;
 
   // If non-empty, this string is used as the user agent whenever the tab's
   // NavigationEntries need it overridden.
   std::string user_agent_override;
 
   // Timestamp for when this tab was last modified.
   base::Time timestamp;
 
+  // Timestamp for when this tab was last activated.

[sky, 2015/05/22 03:00:19]

Add a comment about being careful as value is only useful when comparing against
other last_active_times.

[Georges Khalil, 2015/05/22 20:14:09]

Done.

+  base::TimeTicks last_active_time;
+
   std::vector<sessions::SerializedNavigationEntry> navigations;
 
   // For reassociating sessionStorage.
   std::string session_storage_persistent_id;
 
   // Ids of the currently assigned variations which should be sent to sync.
   std::vector<variations::VariationID> variation_ids;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SessionTab);
@@ skipping 54 matching lines @@
 
   std::string app_name;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SessionWindow);
 };
 
 }  // namespace sessions
 
 #endif  // COMPONENTS_SESSIONS_SESSION_TYPES_H_