cros: Port SAML support to webview sign-in.

chrome/browser/resources/gaia_auth/channel.js

 // Copyright 2013 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.
 
 /**
  * Channel to the background script.
  */
 function Channel() {
 }
 
@@ skipping 91 matching lines @@
     } else if (name == Channel.INTERNAL_REPLY_MESSAGE) {
       var callback = this.internalRequestCallbacks_[msg.requestId];
       delete this.internalRequestCallbacks_[msg.requestId];
       if (callback)
         callback(msg.result);
     } else {
       this.invokeMessageCallbacks_(msg);
     }
   }
 };
+
+/**
+ * Class factory.
+ * @return {Channel}
+ */
+Channel.create = function() {
+  return new Channel();
+};