Make CUPS USB printing play better with the settings page. This change does several things:

chrome/browser/resources/settings/printing_page/cups_add_printer_dialog_util.js

 // Copyright 2016 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.
 
 /** 'add-printers-list' is the list of discovered printers. */
 Polymer({
   is: 'add-printer-list',
 
   properties: {
     /** @type {!Array<!CupsPrinterInfo>} */
     printers: {
       type: Array,
       notify: true,
     },
 
     /** @type {!CupsPrinterInfo} */
-    selectedPrinter: {
+    newPrinter: {
       type: Object,
       notify: true,
     },
   },
 
   /**
    * @param {{model:Object}} event
    * @private
    */
   onSelect_: function(event) {
-    this.selectedPrinter = event.model.item;
+    this.newPrinter = event.model.item;
   },
 });
 
 /** 'drop-down-search-box' implements a search box with suggestions dropdown. */
 Polymer({
   is: 'drop-down-search-box',
 
   properties: {
     /** @type {!Array<string>} */
     items: {
@@ skipping 68 matching lines @@
 
   /** @private */
   attached: function() {
     this.$.dialog.showModal();
   },
 
   close: function() {
     this.$.dialog.close();
   },
 });