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.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.
 
 /**
  * @fileoverview 'settings-cups-add-printer-dialog' includes multiple dialogs to
  * set up a new CUPS printer.
  * Subdialogs include:
  * - 'add-printer-discovery-dialog' is a dialog showing discovered printers on
  *   the network that are available for setup.
@@ skipping 27 matching lines @@
 
   behaviors: [WebUIListenerBehavior],
 
   properties: {
     /** @type {!Array<!CupsPrinterInfo>|undefined} */
     discoveredPrinters: {
       type: Array,
     },
 
     /** @type {!CupsPrinterInfo} */
-    selectedPrinter: {
+    newPrinter: {
       type: Object,
       notify: true,
     },
 
     discovering_: {
       type: Boolean,
       value: true,
     },
   },
 
   /** @override */
   ready: function() {
     settings.CupsPrintersBrowserProxyImpl.getInstance().
         startDiscoveringPrinters();
     this.addWebUIListener('on-printer-discovered',
                           this.onPrinterDiscovered_.bind(this));
     this.addWebUIListener('on-printer-discovery-done',
                           this.onPrinterDiscoveryDone_.bind(this));
     this.addWebUIListener('on-printer-discovery-failed',
                           this.onPrinterDiscoveryDone_.bind(this));
   },
 
   /**
    * @param {!Array<!CupsPrinterInfo>} printers
    * @private
    */
   onPrinterDiscovered_: function(printers) {
-    this.discovering_ = true;
-    if (!this.discoveredPrinters) {
-      this.discoveredPrinters = printers;
-    } else {
-      for (var i = 0; i < printers.length; i++)
-        this.push('discoveredPrinters', printers[i]);
+    this.discoveredPrinters = printers;
+    if (!this.discovering_) {
+      // This update happened after we already finished the initial scan, so
+      // re-run the discovery done logic.
+      this.onPrinterDiscoveryDone_();
     }
   },
 
   /** @private */
   onPrinterDiscoveryDone_: function() {
     this.discovering_ = false;
     this.$$('add-printer-list').style.maxHeight = kPrinterListFullHeight + 'px';
     this.$.noPrinterMessage.hidden = !!this.discoveredPrinters;
   },
 
   /** @private */
   stopDiscoveringPrinters_: function() {
     settings.CupsPrintersBrowserProxyImpl.getInstance().
         stopDiscoveringPrinters();
     this.discovering_ = false;
   },
 
   /** @private */
   switchToManualAddDialog_: function() {
     this.stopDiscoveringPrinters_();
+    // If the user has a printer selected in the discovery list, we *don't* want
+    // to use that if we go to add a printer manually, so reset newPrinter.
+    this.newPrinter =  {
+      printerAddress: '',
+      printerDescription: '',
+      printerId: '',
+      printerManufacturer: '',
+      printerModel: '',
+      printerName: '',
+      printerPPDPath: '',
+      printerProtocol: 'ipp',
+      printerQueue: 'ipp/print',
+      printerStatus: '',
+    };
     this.$$('add-printer-dialog').close();
     this.fire('open-manually-add-printer-dialog');
   },
 
   /** @private */
   onCancelTap_: function() {
     this.stopDiscoveringPrinters_();
     this.$$('add-printer-dialog').close();
   },
 
   /** @private */
-  switchToConfiguringDialog_: function() {
+  switchToManufacturerDialog_: function() {
     this.stopDiscoveringPrinters_();
     this.$$('add-printer-dialog').close();
-    this.fire('open-configuring-printer-dialog');
+    this.fire('open-manufacturer-model-dialog');
   },
 });
 
 Polymer({
   is: 'add-printer-manually-dialog',
 
   properties: {
     /** @type {!CupsPrinterInfo} */
     newPrinter: {
       type: Object,
@@ skipping 183 matching lines @@
   },
 });
 
 Polymer({
   is: 'settings-cups-add-printer-dialog',
 
   behaviors: [WebUIListenerBehavior],
 
   properties: {
     /** @type {!CupsPrinterInfo} */
-    selectedPrinter: {
-      type: Object,
-    },
-
-    /** @type {!CupsPrinterInfo} */
     newPrinter: {
       type: Object,
     },
 
     /** @type {boolean} whether the new printer setup is failed. */
     setupFailed: {
       type: Boolean,
       value: false,
     },
 
@@ skipping 27 matching lines @@
   },
 
   /** @override */
   ready: function() {
     this.addWebUIListener('on-add-cups-printer', this.onAddPrinter_.bind(this));
   },
 
   /** Opens the Add printer discovery dialog. */
   open: function() {
     this.resetData_();
-    this.switchDialog_(
-        '', AddPrinterDialogs.MANUALLY, 'showManuallyAddDialog_');
+    this.switchDialog_('', AddPrinterDialogs.DISCOVERY, 'showDiscoveryDialog_');
   },
 
   /**
    * Reset all the printer data in the Add printer flow.
    * @private
    */
   resetData_: function() {
-    if (this.selectedPrinter)
-      this.selectedPrinter = this.getEmptyPrinter_();
     if (this.newPrinter)
       this.newPrinter = this.getEmptyPrinter_();
     this.setupFailed = false;
   },
 
   /**
    * @return {!CupsPrinterInfo}
    * @private
    */
   getEmptyPrinter_: function() {
@@ skipping 24 matching lines @@
   },
 
   /** @private */
   openConfiguringPrinterDialog_: function() {
     this.switchDialog_(
         this.currentDialog_, AddPrinterDialogs.CONFIGURING,
         'showConfiguringDialog_');
     if (this.previousDialog_ == AddPrinterDialogs.DISCOVERY) {
       this.configuringDialogTitle =
           loadTimeData.getString('addPrintersNearbyTitle');
-      settings.CupsPrintersBrowserProxyImpl.getInstance().addCupsPrinter(
-          this.selectedPrinter);
     } else if (this.previousDialog_ == AddPrinterDialogs.MANUFACTURER) {
       this.configuringDialogTitle =
           loadTimeData.getString('addPrintersManuallyTitle');
-      settings.CupsPrintersBrowserProxyImpl.getInstance().addCupsPrinter(
-          this.newPrinter);
     }
+    settings.CupsPrintersBrowserProxyImpl.getInstance().addCupsPrinter(
+        this.newPrinter);
   },
 
   /** @private */
   openManufacturerModelDialog_: function() {
     this.switchDialog_(this.currentDialog_, AddPrinterDialogs.MANUFACTURER,
                        'showManufacturerDialog_');
   },
 
   /** @private */
   configuringDialogClosed_: function() {
@@ skipping 25 matching lines @@
         this.set(domIfBooleanName, false);
       }.bind(this));
     });
   },
 
   /**
    * @return {string} The name of the current printer in configuration.
    * @private
    */
   getConfiguringPrinterName_: function() {
-    if (this.previousDialog_ == AddPrinterDialogs.DISCOVERY)
-      return this.selectedPrinter.printerName;
-    if (this.previousDialog_ == AddPrinterDialogs.MANUALLY ||
+    if (this.previousDialog_ == AddPrinterDialogs.DISCOVERY ||
+        this.previousDialog_ == AddPrinterDialogs.MANUALLY ||
         this.previousDialog_ == AddPrinterDialogs.MANUFACTURER) {
       return this.newPrinter.printerName;
     }
     return '';
   },
 
   /**
    * @param {boolean} success
    * @param {string} printerName
    * @private
    */
   onAddPrinter_: function(success, printerName) {
     this.$$('add-printer-configuring-dialog').close();
     if (success)
       return;
 
     if (this.previousDialog_ == AddPrinterDialogs.MANUFACTURER) {
       this.setupFailed = true;
     }
   },
 });