CUPS: ADD button should be disabled if there is no selected printer.

Bug: 761718
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: If330d3684b0e01b5de32c271b30acac1e665d4b5
Reviewed-on: https://chromium-review.googlesource.com/756324
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515272}

chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.html

@@ -61,7 +61,7 @@
             $i18n{cancelButtonText}
           </paper-button>
           <paper-button class="action-button" id="addPrinterButton"
-              disabled="[[!selectedPrinter]]"
+              disabled="[[!canAddPrinter_(selectedPrinter)]]"
               on-tap="switchToConfiguringDialog_">
             $i18n{addPrinterButtonText}
           </paper-button>

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

@@ -143,6 +143,15 @@ Polymer({
     this.close();
     this.fire('open-configuring-printer-dialog');
   },
+
+  /**
+   * @param {?CupsPrinterInfo} selectedPrinter
+   * @return {boolean} Whether the add printer button is enabled.
+   * @private
+   */
+  canAddPrinter_: function(selectedPrinter) {
+    return !!selectedPrinter && !!selectedPrinter.printerName;
+  },
 });
 
 Polymer({

chrome/test/data/webui/settings/cups_printer_page_tests.js

@@ -301,7 +301,7 @@ suite('CupsAddPrinterDialogTests', function() {
       printerManufacturer: '',
       printerModel: '',
       printerMakeAndModel: '',
-      printerName: '',
+      printerName: 'printer',
       printerPPDPath: '',
       printerProtocol: 'usb',
       printerQueue: 'moreinfohere',