Interfaceify ClientPlugin in preparation for mocking it.

remoting/remoting_webapp_files.gypi

 # Copyright 2014 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': {
     'remoting_webapp_info_files': [
       'resources/chromoting16.webp',
       'resources/chromoting48.webp',
       'resources/chromoting128.webp',
     ],
 
     # Jscompile proto files.
     # These provide type information for jscompile.
     'remoting_webapp_js_proto_files': [
+      'webapp/client_plugin_interface.js',
+      'webapp/session_connector_interface.js',
       'webapp/js_proto/chrome_proto.js',
       'webapp/js_proto/console_proto.js',
       'webapp/js_proto/dom_proto.js',
       'webapp/js_proto/remoting_proto.js',
     ],
 
     # Auth (apps v1) JavaScript files.
     # These files aren't included directly from main.html. They are
     # referenced from the manifest.json file (appsv1 only).
     'remoting_webapp_js_auth_v1_files': [
@@ skipping 276 matching lines @@
       'webapp/html/dialog_token_refresh_failed.html',
       'webapp/html/toolbar.html',
       'webapp/html/ui_header.html',
       'webapp/html/ui_it2me.html',
       'webapp/html/ui_me2me.html',
       'webapp/html/window_frame.html',
     ],
 
   },
 }