Use helper DeviceChangeHandler to call mousecontrol/tpcontrol whenever a device is attached.

chrome/chrome_browser_chromeos.gypi

 # Copyright (c) 2012 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.
 
 {
   'targets': [
     {
       'target_name': 'browser_chromeos',
       'type': 'static_library',
@@ skipping 696 matching lines @@
         'browser/chromeos/status/data_promo_notification.cc',
         'browser/chromeos/status/data_promo_notification.h',
         'browser/chromeos/status/network_menu.cc',
         'browser/chromeos/status/network_menu.h',
         'browser/chromeos/status/network_menu_icon.cc',
         'browser/chromeos/status/network_menu_icon.h',
         'browser/chromeos/system/ash_system_tray_delegate.cc',
         'browser/chromeos/system/ash_system_tray_delegate.h',
         'browser/chromeos/system/automatic_reboot_manager.cc',
         'browser/chromeos/system/automatic_reboot_manager.h',
+        'browser/chromeos/system/device_change_handler.cc',
+        'browser/chromeos/system/device_change_handler.h',
         'browser/chromeos/system/input_device_settings.cc',
         'browser/chromeos/system/input_device_settings.h',
         'browser/chromeos/system/pointer_device_observer.cc',
         'browser/chromeos/system/pointer_device_observer.h',
         'browser/chromeos/system/statistics_provider.cc',
         'browser/chromeos/system/statistics_provider.h',
         'browser/chromeos/system/syslogs_provider.cc',
         'browser/chromeos/system/syslogs_provider.h',
         'browser/chromeos/system/timezone_settings.cc',
         'browser/chromeos/system/timezone_settings.h',
@@ skipping 194 matching lines @@
         'browser/chromeos/attestation/attestation_key_payload.proto',
       ],
       'variables': {
         'proto_in_dir': 'browser/chromeos/attestation',
         'proto_out_dir': 'chrome/browser/chromeos/attestation',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }