Print Preview: Show error message if text is typed in Copies section

chrome/browser/resources/print_preview/data/ticket_items/copies.js

Index: chrome/browser/resources/print_preview/data/ticket_items/copies.js
diff --git a/chrome/browser/resources/print_preview/data/ticket_items/copies.js b/chrome/browser/resources/print_preview/data/ticket_items/copies.js
index 91e6acf475ddeafc719e53535df5c29632628fcb..22098be470a72c5b770ceba194f34cb50499c2ef 100644
--- a/chrome/browser/resources/print_preview/data/ticket_items/copies.js
+++ b/chrome/browser/resources/print_preview/data/ticket_items/copies.js
@@ -24,14 +24,7 @@ cr.define('print_preview.ticket_items', function() {
 
     /** @override */
     wouldValueBeValid: function(value) {
-      if (/[^\d]+/.test(value)) {
-        return false;
-      }
-      var copies = parseInt(value, 10);
-      if (copies > 999 || copies < 1) {
-        return false;
-      }
-      return true;
+      return value != '';
     },
 
     /** @override */
@@ -41,7 +34,8 @@ cr.define('print_preview.ticket_items', function() {
 
     /** @return {number} The number of copies indicated by the ticket item. */
     getValueAsNumber: function() {
-      return parseInt(this.getValue(), 10);
+      var value = this.getValue();
+      return value == '' ? 0 : parseInt(value, 10);
     },
 
     /** @override */