Add OVERRIDE to chrome/browser/chromeos/.

chrome/browser/chromeos/boot_times_loader.h

Index: chrome/browser/chromeos/boot_times_loader.h
diff --git a/chrome/browser/chromeos/boot_times_loader.h b/chrome/browser/chromeos/boot_times_loader.h
index dfd73d2e4231286c35360dff160615195ae55f82..962009d985eb59abc7c5f2936247bd5938ab7e42 100644
--- a/chrome/browser/chromeos/boot_times_loader.h
+++ b/chrome/browser/chromeos/boot_times_loader.h
@@ -11,6 +11,7 @@
 
 #include "base/atomic_sequence_num.h"
 #include "base/callback_old.h"
+#include "base/compiler_specific.h"
 #include "base/time.h"
 #include "content/browser/cancelable_request.h"
 #include "content/browser/renderer_host/render_widget_host.h"
@@ -105,7 +106,7 @@ class BootTimesLoader
   // content::NotificationObserver implementation.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
-                       const content::NotificationDetails& details);
+                       const content::NotificationDetails& details) OVERRIDE;
 
   // Writes the logout times to a /tmp/logout-times-sent. Unlike login
   // times, we manually call this function for logout times, as we cannot