Prioritize ARC instance only when it is needed

components/arc/BUILD.gn

 # 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.
 
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 
 static_library("arc") {
   sources = [
     "arc_service_manager.cc",
     "arc_service_manager.h",
     "audio/arc_audio_bridge.cc",
     "audio/arc_audio_bridge.h",
     "bluetooth/arc_bluetooth_bridge.cc",
     "bluetooth/arc_bluetooth_bridge.h",
     "bluetooth/bluetooth_struct_traits.cc",
     "bluetooth/bluetooth_struct_traits.h",
     "bluetooth/bluetooth_type_converters.cc",
     "bluetooth/bluetooth_type_converters.h",
-    "boot_phase_monitor/arc_boot_phase_monitor_bridge.cc",
-    "boot_phase_monitor/arc_boot_phase_monitor_bridge.h",
     "clipboard/arc_clipboard_bridge.cc",
     "clipboard/arc_clipboard_bridge.h",
     "crash_collector/arc_crash_collector_bridge.cc",
     "crash_collector/arc_crash_collector_bridge.h",
     "ime/arc_ime_bridge.h",
     "ime/arc_ime_bridge_impl.cc",
     "ime/arc_ime_bridge_impl.h",
     "ime/arc_ime_service.cc",
     "ime/arc_ime_service.h",
     "intent_helper/activity_icon_loader.cc",
@@ skipping 186 matching lines @@
     "//testing/gtest",
     "//ui/aura",
     "//ui/aura:test_support",
     "//ui/base:test_support",
     "//ui/base/ime",
     "//ui/events",
     "//ui/events:dom_keycode_converter",
     "//url:url",
   ]
 }