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

Index: chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
diff --git a/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js b/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
index d97e93bd526bea01795afe316b1875f942fcf82c..f85be0d9e7132bdda5aca143d4c8a142db457054 100644
--- a/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
+++ b/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
@@ -45,7 +45,7 @@ Polymer({
     },
 
     /** @type {!CupsPrinterInfo} */
-    selectedPrinter: {
+    newPrinter: {
       type: Object,
       notify: true,
     },
@@ -73,12 +73,11 @@ Polymer({
    * @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_();
     }
   },
 
@@ -115,6 +114,13 @@ Polymer({
     this.$$('add-printer-dialog').close();
     this.fire('open-configuring-printer-dialog');
   },
+
+  /** @private */
+  switchToManufacturerDialog_: function() {
+    this.stopDiscoveringPrinters_();
+    this.$$('add-printer-dialog').close();
+    this.fire('open-manufacturer-model-dialog');
+  },
 });
 
 Polymer({
@@ -317,11 +323,6 @@ Polymer({
 
   properties: {
     /** @type {!CupsPrinterInfo} */
-    selectedPrinter: {
-      type: Object,
-    },
-
-    /** @type {!CupsPrinterInfo} */
     newPrinter: {
       type: Object,
     },
@@ -369,8 +370,7 @@ Polymer({
   /** Opens the Add printer discovery dialog. */
   open: function() {
     this.resetData_();
-    this.switchDialog_(
-        '', AddPrinterDialogs.MANUALLY, 'showManuallyAddDialog_');
+    this.switchDialog_('', AddPrinterDialogs.DISCOVERY, 'showDiscoveryDialog_');
   },
 
   /**
@@ -378,8 +378,6 @@ Polymer({
    * @private
    */
   resetData_: function() {
-    if (this.selectedPrinter)
-      this.selectedPrinter = this.getEmptyPrinter_();
     if (this.newPrinter)
       this.newPrinter = this.getEmptyPrinter_();
     this.setupFailed = false;
@@ -424,14 +422,12 @@ Polymer({
     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 */
@@ -477,9 +473,8 @@ Polymer({
    * @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;
     }