Update chromeos system menu buttons for MD.

ash/common/system/tray/tray_popup_label_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 "ash/common/system/tray/tray_popup_label_button.h"
 
 #include "ash/common/ash_constants.h"
+#include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/system/tray/tray_popup_label_button_border.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/views/painter.h"
 
 namespace ash {
 
 TrayPopupLabelButton::TrayPopupLabelButton(views::ButtonListener* listener,
                                            const base::string16& text)
     : views::LabelButton(listener, text) {
+  DCHECK(!MaterialDesignController::IsSystemTrayMenuMaterial());
   SetBorder(std::unique_ptr<views::Border>(new TrayPopupLabelButtonBorder));
   SetFocusForPlatform();
   set_animate_on_state_change(false);
   SetHorizontalAlignment(gfx::ALIGN_CENTER);
   SetFocusPainter(views::Painter::CreateSolidFocusPainter(
       kFocusBorderColor, gfx::Insets(1, 1, 2, 2)));
 }
 
 TrayPopupLabelButton::~TrayPopupLabelButton() {}
 
 }  // namespace ash