[ios clean] Add placeholder for NTP bookmarks, chrome home and open tabs.

ios/clean/chrome/browser/ui/commands/BUILD.gn

 # Copyright 2016 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.
 
 source_set("commands") {
   sources = [
     "navigation_commands.h",
+    "ntp_commands.h",
     "settings_commands.h",
     "tab_grid_commands.h",
     "tab_strip_commands.h",
     "tools_menu_commands.h",
   ]
   deps = [
     "//base",
   ]
 
   configs += [ "//build/config/compiler:enable_arc" ]
 }