Add old_state parameter to CustomButton::StateChanged

ui/message_center/views/notification_button.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_MESSAGE_CENTER_VIEWS_NOTIFICATION_BUTTON_H_
 #define UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_BUTTON_H_
 
 #include "base/macros.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/views/controls/button/custom_button.h"
@@ skipping 19 matching lines @@
   // Overridden from views::View:
   gfx::Size GetPreferredSize() const override;
   int GetHeightForWidth(int width) const override;
   void OnPaint(gfx::Canvas* canvas) override;
   void OnFocus() override;
   void OnBlur() override;
   void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) override;
 
   // Overridden from views::CustomButton:
-  void StateChanged() override;
+  void StateChanged(ButtonState old_state) override;
 
  private:
   views::ImageView* icon_;
   views::Label* title_;
   std::unique_ptr<views::Painter> focus_painter_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationButton);
 };
 
 }  // namespace message_center
 
 #endif // UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_BUTTON_H_