Move enable extensions define to a build flag.

chrome/browser/renderer_host/chrome_render_message_filter.cc

Index: chrome/browser/renderer_host/chrome_render_message_filter.cc
diff --git a/chrome/browser/renderer_host/chrome_render_message_filter.cc b/chrome/browser/renderer_host/chrome_render_message_filter.cc
index 44b6ad01babc8cbad3bd2467f99b6236fb493160..14d90e85b1ae2ea9389d449106c01297dc8895b7 100644
--- a/chrome/browser/renderer_host/chrome_render_message_filter.cc
+++ b/chrome/browser/renderer_host/chrome_render_message_filter.cc
@@ -29,8 +29,9 @@
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/service_worker_context.h"
+#include "extensions/features/features.h"
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "extensions/browser/guest_view/web_view/web_view_permission_helper.h"
 #include "extensions/browser/guest_view/web_view/web_view_renderer_state.h"
 #include "extensions/common/manifest_handlers/default_locale_handler.h"
@@ -208,7 +209,7 @@ void ChromeRenderMessageFilter::OnRequestFileSystemAccessSyncResponse(
   Send(reply_msg);
 }
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 void ChromeRenderMessageFilter::FileSystemAccessedSyncOnUIThread(
     int render_process_id,
     int render_frame_id,
@@ -264,7 +265,7 @@ void ChromeRenderMessageFilter::OnRequestFileSystemAccess(
   bool allowed =
       cookie_settings_->IsSettingCookieAllowed(origin_url, top_origin_url);
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   bool is_web_view_guest = extensions::WebViewRendererState::GetInstance()
       ->IsGuest(render_process_id_);
   if (is_web_view_guest) {
@@ -293,7 +294,7 @@ void ChromeRenderMessageFilter::OnRequestFileSystemAccess(
                  !allowed));
 }
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 void ChromeRenderMessageFilter::FileSystemAccessedOnUIThread(
     int render_process_id,
     int render_frame_id,