Add OVERRIDE to chrome/browser/chromeos/.

chrome/browser/chromeos/preferences.h

Index: chrome/browser/chromeos/preferences.h
diff --git a/chrome/browser/chromeos/preferences.h b/chrome/browser/chromeos/preferences.h
index 3566986a74ed218538f2bb5be2d9a1f1265840eb..e8b063682ee0025fc079642037da8709452946eb 100644
--- a/chrome/browser/chromeos/preferences.h
+++ b/chrome/browser/chromeos/preferences.h
@@ -9,6 +9,7 @@
 #include <string>
 #include <vector>
 
+#include "base/compiler_specific.h"
 #include "chrome/browser/chromeos/language_preferences.h"
 #include "chrome/browser/prefs/pref_member.h"
 #include "content/public/browser/notification_observer.h"
@@ -39,7 +40,7 @@ class Preferences : public content::NotificationObserver {
   // Overridden from content::NotificationObserver:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
-                       const content::NotificationDetails& details);
+                       const content::NotificationDetails& details) OVERRIDE;
 
  private:
   // This will set the OS settings when the preference changes.