Close notification windows while message loop is still active

ash/system/tray/system_tray_delegate.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 215 matching lines @@
   // Retrieves information about the carrier. If the information cannot be
   // retrieved, returns false.
   virtual bool GetCellularCarrierInfo(std::string* carrier_id,
                                       std::string* toup_url) = 0;
 
   // Opens the top up url.
   virtual void ShowCellularTopupURL(const std::string& topup_url) = 0;
 
   // Shows UI for changing proxy settings.
   virtual void ChangeProxySettings() = 0;
+
+  // Called when the tray is destroyed.
+  virtual void OnTrayDestroyed() = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_