Add OVERRIDE to chrome/browser/sync/.

chrome/browser/sync/util/extensions_activity_monitor.h

Index: chrome/browser/sync/util/extensions_activity_monitor.h
diff --git a/chrome/browser/sync/util/extensions_activity_monitor.h b/chrome/browser/sync/util/extensions_activity_monitor.h
index 0b76ce1cfc31455ed8e2be26dc87c6066518a4d4..a930a52f0350d6c2e5144bfa6427edaf3b0cd8ba 100644
--- a/chrome/browser/sync/util/extensions_activity_monitor.h
+++ b/chrome/browser/sync/util/extensions_activity_monitor.h
@@ -8,6 +8,7 @@
 
 #include <map>
 
+#include "base/compiler_specific.h"
 #include "base/message_loop.h"
 #include "base/synchronization/lock.h"
 #include "content/public/browser/notification_observer.h"
@@ -59,7 +60,7 @@ class ExtensionsActivityMonitor : public content::NotificationObserver {
   // content::NotificationObserver implementation.  Called on |ui_loop_|.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
-                       const content::NotificationDetails& details);
+                       const content::NotificationDetails& details) OVERRIDE;
  private:
   Records records_;
   mutable base::Lock records_lock_;