Move enable extensions define to a build flag.

chrome/browser/ui/tab_helpers.cc

Index: chrome/browser/ui/tab_helpers.cc
diff --git a/chrome/browser/ui/tab_helpers.cc b/chrome/browser/ui/tab_helpers.cc
index 6ffb3654a439913d6e9959db552739cd0adff3d3..3ad2e4ae680d733be64743209a586c0e37ebec38 100644
--- a/chrome/browser/ui/tab_helpers.cc
+++ b/chrome/browser/ui/tab_helpers.cc
@@ -59,6 +59,7 @@
 #include "components/subresource_filter/content/browser/content_subresource_filter_driver_factory.h"
 #include "components/tracing/common/tracing_switches.h"
 #include "content/public/browser/web_contents.h"
+#include "extensions/features/features.h"
 #include "printing/features/features.h"
 
 #if BUILDFLAG(ANDROID_JAVA_UI)
@@ -92,7 +93,7 @@
 #include "chrome/browser/captive_portal/captive_portal_tab_helper.h"
 #endif
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "chrome/browser/extensions/api/web_navigation/web_navigation_api.h"
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
 #include "chrome/browser/extensions/tab_helper.h"
@@ -133,7 +134,7 @@ void TabHelpers::AttachTabHelpers(WebContents* web_contents) {
   web_contents->SetUserData(&kTabContentsAttachedTabHelpersUserDataKey,
                             new base::SupportsUserData::Data());
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   // Set the view type.
   extensions::SetViewType(web_contents, extensions::VIEW_TYPE_TAB_CONTENTS);
 #endif
@@ -246,7 +247,7 @@ void TabHelpers::AttachTabHelpers(WebContents* web_contents) {
   CaptivePortalTabHelper::CreateForWebContents(web_contents);
 #endif
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   extensions::TabHelper::CreateForWebContents(web_contents);
 #endif