views: remove PlatformStyle::CreateLabelButtonBorder

ui/views/style/mac/dialog_button_border_mac.h

-// Copyright 2015 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_VIEWS_STYLE_MAC_DIALOG_BUTTON_BORDER_MAC_H_
-#define UI_VIEWS_STYLE_MAC_DIALOG_BUTTON_BORDER_MAC_H_
-
-#include "base/macros.h"
-#include "ui/views/controls/button/label_button_border.h"
-#include "ui/views/views_export.h"
-
-namespace views {
-
-class LabelButton;
-
-// Skia port of the default button style used for dialogs on Chrome Mac.
-// Originally provided by ConstrainedWindowButton, which used Quartz-backed
-// Cocoa drawing routines.
-class VIEWS_EXPORT DialogButtonBorderMac : public LabelButtonBorder {
- public:
-  DialogButtonBorderMac();
-  ~DialogButtonBorderMac() override;
-
-  // Whether the given |button| should get a highlighted background.
-  static bool ShouldRenderDefault(const LabelButton& button);
-
-  // views::Border:
-  void Paint(const View& view, gfx::Canvas* canvas) override;
-  gfx::Size GetMinimumSize() const override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(DialogButtonBorderMac);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_STYLE_MAC_DIALOG_BUTTON_BORDER_MAC_H_