Add OVERRIDE to chrome/browser/chromeos/.

chrome/browser/chromeos/enterprise_extension_observer.h

Index: chrome/browser/chromeos/enterprise_extension_observer.h
diff --git a/chrome/browser/chromeos/enterprise_extension_observer.h b/chrome/browser/chromeos/enterprise_extension_observer.h
index f342bede83f35c8424928f4d9cc9fd91d12fbf46..d0d4207a4703560d1b3193fde72fa4121d1e8613 100644
--- a/chrome/browser/chromeos/enterprise_extension_observer.h
+++ b/chrome/browser/chromeos/enterprise_extension_observer.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_CHROMEOS_ENTERPRISE_EXTENSION_OBSERVER_H_
 #pragma once
 
+#include "base/compiler_specific.h"
 #include "chrome/common/extensions/extension.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_observer.h"
@@ -28,7 +29,7 @@ class EnterpriseExtensionObserver
 
   virtual void Observe(int type,
                        const content::NotificationSource& source,
-                       const content::NotificationDetails& details);
+                       const content::NotificationDetails& details) OVERRIDE;
 
  private:
   static void CheckExtensionAndNotifyEntd(const FilePath& path);