Use GN buildflags and features to configure account consistency

components/signin/core/common/signin_switches.h

 // Copyright 2014 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 COMPONENTS_SIGNIN_CORE_COMMON_SIGNIN_SWITCHES_H_
 #define COMPONENTS_SIGNIN_CORE_COMMON_SIGNIN_SWITCHES_H_
 
-#include "base/feature_list.h"
-#include "build/build_config.h"
+#include "components/signin/core/common/signin_features.h"
 
 namespace switches {
 
 // These switches should not be queried from CommandLine::HasSwitch() directly.
 // Always go through the helper functions in profile_management_switches.h
 // to properly take into account the state of field trials.
 
 // All switches in alphabetical order. The switches should be documented
 // alongside the definition of their values in the .cc file.
 extern const char kClearTokenService[];
 extern const char kDisableSigninPromo[];
 extern const char kDisableSigninScopedDeviceId[];
 extern const char kEnableRefreshTokenAnnotationRequest[];
 extern const char kEnableSigninPromo[];
 extern const char kExtensionsMultiAccount[];
 
-#if !defined(OS_ANDROID) && !defined(OS_IOS)
+#if !BUILDFLAG(ENABLE_MIRROR)
 // Note: Account consistency (Mirror) is already enabled on mobile platforms, so
 // this switch only exist on desktop platforms.
 extern const char kAccountConsistency[];
 extern const char kAccountConsistencyMirror[];
 extern const char kAccountConsistencyDice[];
 #endif
 
 }  // namespace switches
 
 #endif  // COMPONENTS_SIGNIN_CORE_COMMON_SIGNIN_SWITCHES_H_