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

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index 62f09a8f47ca151e0743309be0a58979b8dcdeb6..86ac67516f244bcab47b4cd7ca22837b99fdcff1 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -351,9 +351,10 @@ class WebContents : public PageNavigator,
   // change.
   virtual void NotifyNavigationStateChanged(InvalidateTypes changed_flags) = 0;
 
-  // Get the last time that the WebContents was made active (either when it was
-  // created or shown with WasShown()).
+  // Get/Set the last time that the WebContents was made active (either when it
+  // was created or shown with WasShown()).
   virtual base::TimeTicks GetLastActiveTime() const = 0;
+  virtual void SetLastActiveTime(base::TimeTicks last_active_time) = 0;
 
   // Invoked when the WebContents becomes shown/hidden.
   virtual void WasShown() = 0;