Start removing deprecated Options UI code

chrome/browser/flag_descriptions.h

 // Copyright 2017 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 CHROME_BROWSER_FLAG_DESCRIPTIONS_H_
 #define CHROME_BROWSER_FLAG_DESCRIPTIONS_H_
 
 // Includes needed for macros allowing conditional compilation of some strings.
 #include "build/build_config.h"
 #include "build/buildflag.h"
@@ skipping 211 matching lines @@
 
 extern const char kEnableMaterialDesignExtensionsName[];
 extern const char kEnableMaterialDesignExtensionsDescription[];
 
 extern const char kEnableMaterialDesignFeedbackName[];
 extern const char kEnableMaterialDesignFeedbackDescription[];
 
 extern const char kEnableMaterialDesignPolicyPageName[];
 extern const char kEnableMaterialDesignPolicyPageDescription[];
 
-extern const char kEnableMaterialDesignSettingsName[];
-extern const char kEnableMaterialDesignSettingsDescription[];
-
 extern const char kEnableMidiManagerDynamicInstantiationName[];
 extern const char kEnableMidiManagerDynamicInstantiationDescription[];
 
 extern const char kEnableNavigationTracingName[];
 extern const char kEnableNavigationTracingDescription[];
 
 extern const char kEnablePictureInPictureName[];
 extern const char kEnablePictureInPictureDescription[];
 
 extern const char kEnableTokenBindingName[];
@@ skipping 1253 matching lines @@
 #endif  // defined(TOOLKIT_VIEWS) || defined(OS_ANDROID)
 
 // ============================================================================
 // Don't just add flags to the end, put them in the right section in
 // alphabetical order. See top instructions for more.
 // ============================================================================
 
 }  // namespace flag_descriptions
 
 #endif  // CHROME_BROWSER_FLAG_DESCRIPTIONS_H_