Convert enable_one_click_signin to new buildflag system

chrome/common/url_constants.h

 // Copyright (c) 2012 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.
 
 // Contains constants for known URLs and portions thereof.
 
 #ifndef CHROME_COMMON_URL_CONSTANTS_H_
 #define CHROME_COMMON_URL_CONSTANTS_H_
 
 #include <stddef.h>
@@ skipping 346 matching lines @@
 extern const char kChromeHelpViaMenuURL[];
 extern const char kChromeHelpViaWebUIURL[];
 
 #if defined(OS_CHROMEOS)
 // Accessibility help link for Chrome.
 extern const char kChromeAccessibilityHelpURL[];
 // Accessibility settings link for Chrome.
 extern const char kChromeAccessibilitySettingsURL[];
 #endif
 
-#if defined (ENABLE_ONE_CLICK_SIGNIN)
+#if BUILDFLAG(ENABLE_ONE_CLICK_SIGNIN)
 // "Learn more" URL for the one click signin infobar.
 extern const char kChromeSyncLearnMoreURL[];
 
 // "Learn more" URL for the "Sign in with a different account" confirmation
 // dialog.
 extern const char kChromeSyncMergeTroubleshootingURL[];
 #endif
 
 #if defined(OS_MACOSX)
 // "Learn more" URL for the enterprise sign-in confirmation dialog.
@@ skipping 196 matching lines @@
 extern const char kWindowsXPVistaDeprecationURL[];
 #endif
 
 // The URL for the Bluetooth Overview help center article in the Web Bluetooth
 // Chooser.
 extern const char kChooserBluetoothOverviewURL[];
 
 }  // namespace chrome
 
 #endif  // CHROME_COMMON_URL_CONSTANTS_H_