Remove MaterialDesignController::IsModeMaterial

ui/native_theme/native_theme_dark_win.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_NATIVE_THEME_NATIVE_THEME_DARK_WIN_H_
-#define UI_NATIVE_THEME_NATIVE_THEME_DARK_WIN_H_
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "ui/native_theme/native_theme_win.h"
-
-namespace ui {
-
-class NATIVE_THEME_EXPORT NativeThemeDarkWin : public NativeThemeWin {
- public:
-  static NativeThemeDarkWin* instance();
-
- private:
-  NativeThemeDarkWin();
-  ~NativeThemeDarkWin() override;
-
-  // Overridden from NativeThemeBase:
-  SkColor GetSystemColor(ColorId color_id) const override;
-
-  DISALLOW_COPY_AND_ASSIGN(NativeThemeDarkWin);
-};
-
-}  // namespace ui
-
-#endif  // UI_NATIVE_THEME_NATIVE_THEME_DARK_WIN_H_