Print Preview: Print on numpad enter

Bug: 898444
Change-Id: Icadd1866dc0292993b6e52b06198363868af4a81
Reviewed-on: https://chromium-review.googlesource.com/c/1297458Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602521}

chrome/browser/resources/print_preview/new/app.js

@@ -273,7 +273,8 @@ Polymer({
       }
     }
 
-    if (e.code == 'Enter' && this.state == print_preview_new.State.READY &&
+    if ((e.code === 'Enter' || e.code === 'NumpadEnter') &&
+        this.state === print_preview_new.State.READY &&
         this.openDialogs_.length === 0) {
       const activeElementTag = e.path[0].tagName;
       if (['PAPER-BUTTON', 'BUTTON', 'SELECT', 'A', 'CR-CHECKBOX'].includes(