chromoting: Add JS externs for qunit.

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.
 
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 # .JMML. .JMM.`Mbmmd' `Moo9^Yo.`Wbmd"MML..JMML  JMML  JMML.`Mbmmd'
 #
 # Please keep this file in sync with remoting/remoting_webapp_files.gypi
 # and remoting/app_remoting_webapp_files.gypi.
 
+# JSCompiler externs.
+remoting_webapp_js_externs = [ "externs/qunit.js" ]
+
 # Jscompile proto files.
 # These provide type information for jscompile.
 remoting_webapp_js_proto_files = [
   "js_proto/chrome_proto.js",
   "js_proto/chrome_cast_proto.js",
   "js_proto/dom_proto.js",
   "js_proto/remoting_proto.js",
 ]
 
 #
@@ skipping 595 matching lines @@
 
 # Files that contain localizable strings.
 app_remoting_webapp_localizable_files =
     [
       ar_main_template,
       ar_feedback_consent_template,
       ar_loading_window_template,
       remoting_webapp_template_message_window,
       remoting_webapp_template_wcs_sandbox,
     ] + ar_main_template_files + ar_all_js_files