Move enable_app_list to a buildflag.

chrome/browser/ui/webui/ntp/ntp_resource_cache.cc

Index: chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
diff --git a/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc b/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
index 8fc2d44495afe1396343bcd4cfbf416649d48016..21df0d4bdfc38284e786976630d3262ad46bebf0 100644
--- a/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
+++ b/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
@@ -33,6 +33,7 @@
 #include "chrome/browser/ui/webui/ntp/app_launcher_handler.h"
 #include "chrome/browser/ui/webui/ntp/new_tab_ui.h"
 #include "chrome/common/chrome_switches.h"
+#include "chrome/common/features.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/browser_resources.h"
@@ -183,7 +184,7 @@ NTPResourceCache::NTPResourceCache(Profile* profile)
   profile_pref_change_registrar_.Add(prefs::kHideWebStoreIcon, callback);
 
   // Some tests don't have a local state.
-#if defined(ENABLE_APP_LIST)
+#if BUILDFLAG(ENABLE_APP_LIST)
   if (g_browser_process->local_state()) {
     local_state_pref_change_registrar_.Init(g_browser_process->local_state());
     local_state_pref_change_registrar_.Add(prefs::kShowAppLauncherPromo,