Access to Chrome via the System Tray should go through the User Manager.

chrome/chrome_browser_ui.gypi

 # Copyright 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.
 
 {
   'variables': {
     'chrome_browser_ui_non_ios_sources': [
       'browser/ui/accelerator_utils.h',
       'browser/ui/android/android_about_app_info.cc',
       'browser/ui/android/android_about_app_info.h',
@@ skipping 883 matching lines @@
       'browser/ui/translate/language_combobox_model.cc',
       'browser/ui/translate/language_combobox_model.h',
       'browser/ui/translate/translate_bubble_factory.cc',
       'browser/ui/translate/translate_bubble_factory.h',
       'browser/ui/translate/translate_bubble_model.h',
       'browser/ui/translate/translate_bubble_model_impl.cc',
       'browser/ui/translate/translate_bubble_model_impl.h',
       'browser/ui/translate/translate_bubble_view_state_transition.cc',
       'browser/ui/translate/translate_bubble_view_state_transition.h',
       'browser/ui/uninstall_browser_prompt.h',
+      'browser/ui/user_manager.h',
       'browser/ui/validation_message_bubble.h',
       'browser/ui/view_ids.h',
       'browser/ui/web_contents_sizer.h',
       'browser/ui/website_settings/permission_bubble_manager.cc',
       'browser/ui/website_settings/permission_bubble_manager.h',
       'browser/ui/website_settings/permission_bubble_request.h',
       'browser/ui/website_settings/permission_bubble_view.h',
       'browser/ui/website_settings/website_settings.cc',
       'browser/ui/website_settings/website_settings.h',
       'browser/ui/website_settings/website_settings_infobar_delegate.cc',
@@ skipping 2059 matching lines @@
         }],
         ['OS!="android" and OS!="ios"', {
           'dependencies': [
             '../device/bluetooth/bluetooth.gyp:device_bluetooth',
           ],
         }],
       ],
     },
   ],
 }