[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 a28df1cd6ad0fb47078d93336d48f92eabdad79a..09c6228daa4ef9fb59d95fe99116b55358d41101 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -346,10 +346,17 @@ 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 the last time that the WebContent was made active (either when it was
+  // created or shown with WasShown()). If the tab has been restored from a
+  // previous session, this will return the last time it was made active in the
+  // previous session.
   virtual base::TimeTicks GetLastActiveTime() const = 0;
 
+  // Sets the last time that the WebContents was made active. This is used when
+  // tabs are restored so that the initial time is persisted (instead of using
+  // tab creation time).
+  virtual void SetLastActiveTime(base::TimeTicks time) = 0;
+
   // Invoked when the WebContents becomes shown/hidden.
   virtual void WasShown() = 0;
   virtual void WasHidden() = 0;