It is time.

ui/base/models/combobox_model_observer.h

-// Copyright 2013 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 UI_BASE_MODELS_COMBOBOX_MODEL_OBSERVER_H_
-#define UI_BASE_MODELS_COMBOBOX_MODEL_OBSERVER_H_
-
-#include "ui/base/ui_base_export.h"
-
-namespace ui {
-
-class ComboboxModel;
-
-// Observer for the ComboboxModel.
-class UI_BASE_EXPORT ComboboxModelObserver {
- public:
-  // Invoked when |model| has changed in some way. The observer should assume
-  // everything changed.
-  virtual void OnComboboxModelChanged(ComboboxModel* model) = 0;
-
- protected:
-  virtual ~ComboboxModelObserver() {}
-};
-
-}  // namespace ui
-
-#endif  // UI_BASE_MODELS_COMBOBOX_MODEL_OBSERVER_H_