Move enable extensions define to a build flag.

chrome/browser/supervised_user/supervised_user_service_factory.cc

Index: chrome/browser/supervised_user/supervised_user_service_factory.cc
diff --git a/chrome/browser/supervised_user/supervised_user_service_factory.cc b/chrome/browser/supervised_user/supervised_user_service_factory.cc
index 0564b92130bedd9474c233bfa0c212f81ed3730b..113748d4c903ae2b57c6d37d668470d3310e1767 100644
--- a/chrome/browser/supervised_user/supervised_user_service_factory.cc
+++ b/chrome/browser/supervised_user/supervised_user_service_factory.cc
@@ -10,8 +10,9 @@
 #include "chrome/browser/supervised_user/supervised_user_service.h"
 #include "chrome/browser/sync/profile_sync_service_factory.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "extensions/features/features.h"
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "extensions/browser/extension_system_provider.h"
 #include "extensions/browser/extensions_browser_client.h"
 #endif
@@ -37,7 +38,7 @@ SupervisedUserServiceFactory::SupervisedUserServiceFactory()
     : BrowserContextKeyedServiceFactory(
         "SupervisedUserService",
         BrowserContextDependencyManager::GetInstance()) {
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   DependsOn(
       extensions::ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
 #endif