ash: Update system update notification behaviour.

ash/system/tray_update.h

Index: ash/system/tray_update.h
diff --git a/ash/system/tray_update.h b/ash/system/tray_update.h
index 25dd0ec4714706dcf2c21d675d8f9813fc839cbb..3937c3c18f3ee354b3785845eb137839b790390f 100644
--- a/ash/system/tray_update.h
+++ b/ash/system/tray_update.h
@@ -6,6 +6,7 @@
 #define ASH_SYSTEM_TRAY_UPDATE_H_
 
 #include "ash/system/tray/tray_image_item.h"
+#include "ash/system/user/update_observer.h"
 #include "base/memory/scoped_ptr.h"
 
 namespace views {
@@ -14,13 +15,6 @@ class View;
 
 namespace ash {
 
-class ASH_EXPORT UpdateObserver {
- public:
-  virtual ~UpdateObserver() {}
-
-  virtual void OnUpdateRecommended() = 0;
-};
-
 namespace internal {
 
 namespace tray {
@@ -41,12 +35,14 @@ class TrayUpdate : public TrayImageItem,
   virtual void DestroyDetailedView() OVERRIDE;
 
   // Overridden from UpdateObserver.
-  virtual void OnUpdateRecommended() OVERRIDE;
+  virtual void OnUpdateRecommended(UpdateSeverity severity) OVERRIDE;
 
   // Used to nag the user in case the tray has been hidden too long with an
   // unseen update notification.
   scoped_ptr<tray::UpdateNagger> nagger_;
 
+  UpdateObserver::UpdateSeverity severity_;
+
   DISALLOW_COPY_AND_ASSIGN(TrayUpdate);
 };