Remove the most obvious dead code from message center.

ui/message_center/views/message_simple_view.h

-// Copyright (c) 2012 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_MESSAGE_SIMPLE_VIEW_H_
-#define UI_MESSAGE_CENTER_VIEWS_MESSAGE_SIMPLE_VIEW_H_
-
-#include "ui/message_center/views/message_view.h"
-
-namespace message_center {
-
-class MessageCenter;
-class Notification;
-
-// A simple view for a notification entry (icon + message + buttons).
-class MessageSimpleView : public MessageView {
- public:
-  MessageSimpleView(const Notification& notification,
-                    MessageCenter* message_center);
-  virtual ~MessageSimpleView();
-
-  // Overridden from MessageView:
-  virtual void ButtonPressed(views::Button* sender,
-                             const ui::Event& event) OVERRIDE;
-
- protected:
-  // Overridden from views::View:
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
-  virtual int GetHeightForWidth(int width) OVERRIDE;
-  virtual void Layout() OVERRIDE;
-
-  MessageSimpleView();
-
- private:
-  void SetUpView(const Notification& notification);
-
-  scoped_ptr<views::ImageButton> old_style_close_button_;
-  scoped_ptr<views::View> content_view_;
-
-  DISALLOW_COPY_AND_ASSIGN(MessageSimpleView);
-};
-
-}  // namespace message_center
-
-#endif // UI_MESSAGE_CENTER_VIEWS_MESSAGE_SIMPLE_VIEW_H_