Print Preview: Hook up the print button to initiate a normal print operation....

chrome/browser/resources/print_preview.js

Index: chrome/browser/resources/print_preview.js
===================================================================
--- chrome/browser/resources/print_preview.js	(revision 74317)
+++ chrome/browser/resources/print_preview.js	(working copy)
@@ -9,6 +9,9 @@
  * Window onload handler, sets up the page.
  */
 function load() {
+  $('print-button').addEventListener('click', function(e) {
+    chrome.send('print');
+  });
   $('cancel-button').addEventListener('click', function(e) {
     window.close();
   });