Add deprecation messages.

remoting/webapp/files.gni

 # 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.
 
 # `7MM"""Mq.                       `7MM
 #   MM   `MM.                        MM
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 #   MMmmdM9  ,M'   Yb 8)   MM ,AP    MM    MM    MM    MM ,M'   Yb
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@@ skipping 87 matching lines @@
   "base/js/viewport_unittest.js",
   "base/js/window_shape_unittest.js",
   "base/js/window_message_dispatcher_unittest.js",
   "base/js/xhr_event_writer_unittest.js",
   "base/js/xhr_unittest.js",
   "base/js/xmpp_connection_unittest.js",
   "base/js/xmpp_error_cache_unittest.js",
   "base/js/xmpp_login_handler_unittest.js",
   "base/js/xmpp_stream_parser_unittest.js",
   "crd/js/apps_v2_migration_unittest.js",
+  "crd/js/butter_bar_unittest.js",
   "crd/js/combined_host_list_api_unittest.js",
   "crd/js/gcd_client_unittest.js",
   "crd/js/gcd_client_with_mock_xhr_unittest.js",
   "crd/js/gnubby_auth_handler_unittest.js",
   "crd/js/host_controller_unittest.js",
   "crd/js/host_daemon_facade_unittest.js",
   "crd/js/host_table_entry_unittest.js",
   "crd/js/legacy_host_list_api_unittest.js",
   "crd/js/menu_button_unittest.js",
   "crd/js/mock_xhr_unittest.js",
@@ skipping 449 matching lines @@
       "webapp/crd/manifest.json.jinja2",
       remoting_webapp_template_background,
       remoting_webapp_template_main,
       remoting_webapp_template_message_window,
       remoting_webapp_template_wcs_sandbox,
     ] + remoting_webapp_template_files + remoting_webapp_crd_js_files
 
 webapp_js_files = remoting_webapp_unittest_html_all_js_files +
                   remoting_webapp_wcs_sandbox_html_js_files +
                   remoting_webapp_background_html_js_files