It is time.

ui/base/models/combobox_model.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 UI_BASE_MODELS_COMBOBOX_MODEL_H_
-#define UI_BASE_MODELS_COMBOBOX_MODEL_H_
-
-#include "base/strings/string16.h"
-#include "ui/base/ui_base_export.h"
-
-namespace ui {
-
-class ComboboxModelObserver;
-
-// A data model for a combo box.
-class UI_BASE_EXPORT ComboboxModel {
- public:
-  // Returns the number of items in the combo box.
-  virtual int GetItemCount() const = 0;
-
-  // Returns the string at the specified index.
-  virtual base::string16 GetItemAt(int index) = 0;
-
-  // Should return true if the item at |index| is a non-selectable separator
-  // item.
-  virtual bool IsItemSeparatorAt(int index);
-
-  // The index of the item that is selected by default (before user
-  // interaction).
-  virtual int GetDefaultIndex() const;
-
-  // Returns true if the item at |index| is enabled.
-  virtual bool IsItemEnabledAt(int index) const;
-
-  // Adds/removes an observer. Override if model supports mutation.
-  virtual void AddObserver(ComboboxModelObserver* observer) {}
-  virtual void RemoveObserver(ComboboxModelObserver* observer) {}
-
- protected:
-  virtual ~ComboboxModel() {}
-};
-
-}  // namespace ui
-
-#endif  // UI_BASE_MODELS_COMBOBOX_MODEL_H_