| // Copyright 2021 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 CHROME_BROWSER_THEMES_THEME_SERVICE_OBSERVER_H_ | 
 | #define CHROME_BROWSER_THEMES_THEME_SERVICE_OBSERVER_H_ | 
 |  | 
 | #include "base/observer_list_types.h" | 
 |  | 
 | class ThemeServiceObserver : public base::CheckedObserver { | 
 |  public: | 
 |   // Called when the user has changed the browser theme. | 
 |   virtual void OnThemeChanged() = 0; | 
 |  | 
 |  protected: | 
 |   ~ThemeServiceObserver() override = default; | 
 | }; | 
 |  | 
 | #endif  // CHROME_BROWSER_THEMES_THEME_SERVICE_OBSERVER_H_ |