Add old_state parameter to CustomButton::StateChanged

ui/message_center/views/notification_button.cc

 // 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.
 
 #include "ui/message_center/views/notification_button.h"
 
 #include "ui/gfx/canvas.h"
 #include "ui/message_center/message_center_style.h"
 #include "ui/message_center/views/constants.h"
 #include "ui/views/background.h"
@@ skipping 91 matching lines @@
 }
 
 void NotificationButton::ViewHierarchyChanged(
     const ViewHierarchyChangedDetails& details) {
   // We disable view hierarchy change detection in the parent
   // because it resets the hoverstate, which we do not want
   // when we update the view to contain a new label or image.
   views::View::ViewHierarchyChanged(details);
 }
 
-void NotificationButton::StateChanged() {
+void NotificationButton::StateChanged(ButtonState old_state) {
   if (state() == STATE_HOVERED || state() == STATE_PRESSED) {
     set_background(views::Background::CreateSolidBackground(
         message_center::kHoveredButtonBackgroundColor));
   } else {
     set_background(views::Background::CreateSolidBackground(
         kNotificationBackgroundColor));
   }
 }
 
 }  // namespace message_center