Move enable extensions define to a build flag.

chrome/browser/ui/omnibox/chrome_omnibox_edit_controller.cc

 // Copyright 2015 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.
 
 #include "chrome/browser/ui/omnibox/chrome_omnibox_edit_controller.h"
 
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/command_updater.h"
 #include "components/toolbar/toolbar_model.h"
+#include "extensions/features/features.h"
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "chrome/browser/ui/extensions/settings_api_bubble_helpers.h"
 #endif
 
 ChromeOmniboxEditController::ChromeOmniboxEditController(
     CommandUpdater* command_updater)
     : command_updater_(command_updater) {}
 
 ChromeOmniboxEditController::~ChromeOmniboxEditController() {}
 
 void ChromeOmniboxEditController::OnAutocompleteAccept(
     const GURL& destination_url,
     WindowOpenDisposition disposition,
     ui::PageTransition transition,
     AutocompleteMatchType::Type match_type) {
   OmniboxEditController::OnAutocompleteAccept(destination_url, disposition,
                                               transition, match_type);
   if (command_updater_)
     command_updater_->ExecuteCommand(IDC_OPEN_CURRENT_URL);
 
-#if defined(ENABLE_EXTENSIONS)
+#if BUILDFLAG(ENABLE_EXTENSIONS)
   extensions::MaybeShowExtensionControlledSearchNotification(
       GetWebContents(), match_type);
 #endif
 }
 
 void ChromeOmniboxEditController::OnInputInProgress(bool in_progress) {
   GetToolbarModel()->set_input_in_progress(in_progress);
   UpdateWithoutTabRestore();
 }