Add OVERRIDE to chrome/browser/chromeos/.

chrome/browser/chromeos/upgrade_detector_chromeos.h

Index: chrome/browser/chromeos/upgrade_detector_chromeos.h
diff --git a/chrome/browser/chromeos/upgrade_detector_chromeos.h b/chrome/browser/chromeos/upgrade_detector_chromeos.h
index e343d6b03ce5a4c771152426629f977ca8c68ce7..8444d717f19f8afe35a36e4e6a89bbebecefb07d 100644
--- a/chrome/browser/chromeos/upgrade_detector_chromeos.h
+++ b/chrome/browser/chromeos/upgrade_detector_chromeos.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include "base/timer.h"
+#include "base/compiler_specific.h"
 #include "chrome/browser/chromeos/cros/update_library.h"
 #include "chrome/browser/upgrade_detector.h"
 
@@ -34,7 +35,7 @@ class UpgradeDetectorChromeos : public UpgradeDetector,
 
   // chromeos::UpdateLibrary::Observer implementation.
   virtual void UpdateStatusChanged(
-      const chromeos::UpdateLibrary::Status& status);
+      const chromeos::UpdateLibrary::Status& status) OVERRIDE;
 
   // The function that sends out a notification (after a certain time has
   // elapsed) that lets the rest of the UI know we should start notifying the