[CUPS] Implement the Add Printer dialogs.

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: {
+      type: Object,
+      notify: true,
+    },
+  },
+
+  /**
+   * @param {{model:Object}} event
+   * @private
+   */
+  onSelect_: function(event) {
+    this.selectedPrinter = event.model.item;
+  },
+});
+
+/** 'add-printer-dialog' is the template of the Add Printer dialog. */
+Polymer({
+  is: 'add-printer-dialog',
+
+  /** @private */
+  attached: function() {
+    this.$.dialog.showModal();
+  },
+
+  close: function() {
+    this.$.dialog.close();
+  },
+});