Replace printer queue placeholder with a value in manual printers

- Fixes a bug where the default text for printer queue would appear
  grey, which made it seem inactive.

Bug: 958740
Test: end to end manual, browsertests
Change-Id: I18bdcc5a6984f737cabfaa7ab06a7714b5176194
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1663075Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Reviewed-by: Sean Kau <skau@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671488}

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

@@ -134,7 +134,7 @@
           </div>
         </div>
         <div class="settings-box two-line">
-          <cr-input placeholder="ipp/print" label="$i18n{printerQueue}"
+          <cr-input label="$i18n{printerQueue}"
               value="{{newPrinter.printerQueue}}" maxlength=64>
           </cr-input>
         </div>

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

@@ -56,7 +56,7 @@ function getEmptyPrinter_() {
     },
     printerPpdReferenceResolved: false,
     printerProtocol: 'ipp',
-    printerQueue: '',
+    printerQueue: 'ipp/print',
     printerStatus: '',
   };
 }
@@ -258,10 +258,6 @@ Polymer({
   /** @private */
   addPressed_: function() {
     this.addPrinterInProgress_ = true;
-    // Set the default printer queue to be "ipp/print".
-    if (!this.newPrinter.printerQueue) {
-      this.set('newPrinter.printerQueue', 'ipp/print');
-    }
 
     if (this.newPrinter.printerProtocol == 'ipp' ||
         this.newPrinter.printerProtocol == 'ipps') {