Use device Robot Account to access Cloud Print.

chrome/browser/resources/print_preview/print_preview.js

 // Copyright (c) 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.
 
 // TODO(rltoscano): Move data/* into print_preview.data namespace
 
 var localStrings = new LocalStrings(templateData);
 
 <include src="component.js"/>
 
@@ skipping 478 matching lines @@
 
     /**
      * Calls when the native layer enables Google Cloud Print integration.
      * Fetches the user's cloud printers.
      * @param {cr.Event} event Contains the base URL of the Google Cloud Print
      *     service.
      * @private
      */
     onCloudPrintEnable_: function(event) {
       this.cloudPrintInterface_ =
-          new cloudprint.CloudPrintInterface(event.baseCloudPrintUrl);
+          new cloudprint.CloudPrintInterface(event.baseCloudPrintUrl,
+                                             this.nativeLayer_);
       this.tracker.add(
           this.cloudPrintInterface_,
           cloudprint.CloudPrintInterface.EventType.SUBMIT_DONE,
           this.onCloudPrintSubmitDone_.bind(this));
       this.tracker.add(
           this.cloudPrintInterface_,
           cloudprint.CloudPrintInterface.EventType.SEARCH_FAILED,
           this.onCloudPrintError_.bind(this));
       this.tracker.add(
           this.cloudPrintInterface_,
@@ skipping 415 matching lines @@
 <include src="search/recent_destination_list.js"/>
 <include src="search/destination_list_item.js"/>
 <include src="search/destination_search.js"/>
 <include src="search/search_box.js"/>
 <include src="search/fedex_tos.js"/>
 
 window.addEventListener('DOMContentLoaded', function() {
   printPreview = new print_preview.PrintPreview();
   printPreview.initialize();
 });