Update TrayPopupHeaderButton Visual Feedback

ash/system/tray/special_popup_row.h

 // Copyright (c) 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 ASH_SYSTEM_TRAY_SPECIAL_POPUP_ROW_H_
 #define ASH_SYSTEM_TRAY_SPECIAL_POPUP_ROW_H_
 
+#include "ash/ash_export.h"
 #include "ui/gfx/size.h"
 #include "ui/views/view.h"
 
 namespace views {
 class Label;
 }
 
 namespace ash {
 class ThrobberView;
 class TrayItemView;
 class TrayPopupHeaderButton;
 class ViewClickListener;
 
 // The 'special' looking row in the uber-tray popups. This is usually the bottom
 // row in the popups, and has a fixed height.
-class SpecialPopupRow : public views::View {
+class ASH_EXPORT SpecialPopupRow : public views::View {
  public:
   SpecialPopupRow();
   ~SpecialPopupRow() override;
 
   void SetTextLabel(int string_id, ViewClickListener* listener);
   void SetContent(views::View* view);
 
   void AddButton(TrayPopupHeaderButton* button);
   void AddThrobber(ThrobberView* throbber);
 
   views::View* content() const { return content_; }
 
  private:
   // Overridden from views::View.
   gfx::Size GetPreferredSize() const override;
   int GetHeightForWidth(int width) const override;
   void Layout() override;
 
   views::View* content_;
   views::View* button_container_;
   views::Label* text_label_;
 
   DISALLOW_COPY_AND_ASSIGN(SpecialPopupRow);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SPECIAL_POPUP_ROW_H_