Add OVERRIDE to chrome/browser/.

chrome/browser/printing/print_preview_tab_controller.h

 // Copyright (c) 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.
 
 // For print preview, a print preview (PP) tab is linked with the initiator tab
 // that initiated the printing operation. If the tab initiates a second
 // printing operation while the first print preview tab is still open, that PP
 // tab is focused/activated. There may be more than one PP tab open. There is a
 // 1:1 relationship between PP tabs and initiating tabs. This class manages PP
 // tabs and initiator tabs.
@@ skipping 42 matching lines @@
   // Returns NULL if no preview tab exists for |tab|.
   TabContentsWrapper* GetPrintPreviewForTab(TabContentsWrapper* tab) const;
 
   // Returns initiator tab for |preview_tab|.
   // Returns NULL if no initiator tab exists for |preview_tab|.
   TabContentsWrapper* GetInitiatorTab(TabContentsWrapper* preview_tab);
 
   // content::NotificationObserver implementation.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
-                       const content::NotificationDetails& details);
+                       const content::NotificationDetails& details) OVERRIDE;
 
   // Returns true if |tab| is a print preview tab.
   static bool IsPrintPreviewTab(TabContentsWrapper* tab);
 
   // Returns true if |url| is a print preview url.
   static bool IsPrintPreviewURL(const GURL& url);
 
   // Erase the initiator tab info associated with |preview_tab|.
   void EraseInitiatorTabInfo(TabContentsWrapper* preview_tab);
 
@@ skipping 48 matching lines @@
   // Whether the PrintPreviewTabController is in the middle of creating a
   // print preview tab.
   bool is_creating_print_preview_tab_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewTabController);
 };
 
 }  // namespace printing
 
 #endif  // CHROME_BROWSER_PRINTING_PRINT_PREVIEW_TAB_CONTROLLER_H_