Gut ash::MaterialDesignController, and remove the about:flags entry.

ash/common/test/material_design_controller_test_api.cc

-// Copyright 2016 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/test/material_design_controller_test_api.h"
-
-namespace ash {
-namespace test {
-
-MaterialDesignControllerTestAPI::MaterialDesignControllerTestAPI(
-    MaterialDesignController::Mode mode)
-    : previous_mode_(MaterialDesignController::mode()) {
-  MaterialDesignController::SetMode(mode);
-}
-
-MaterialDesignControllerTestAPI::~MaterialDesignControllerTestAPI() {
-  MaterialDesignController::SetMode(previous_mode_);
-}
-
-// static
-bool MaterialDesignControllerTestAPI::IsMaterial() {
-  return MaterialDesignController::IsMaterial();
-}
-
-// static
-bool MaterialDesignControllerTestAPI::IsMaterialNormal() {
-  return MaterialDesignController::IsMaterialNormal();
-}
-
-// static
-bool MaterialDesignControllerTestAPI::IsMaterialExperimental() {
-  return MaterialDesignController::IsMaterialExperimental();
-}
-
-// static
-MaterialDesignController::Mode MaterialDesignControllerTestAPI::DefaultMode() {
-  return MaterialDesignController::DefaultMode();
-}
-
-// static
-void MaterialDesignControllerTestAPI::Uninitialize() {
-  MaterialDesignController::Uninitialize();
-}
-
-}  // namespace test
-}  // namespace ash