Print Preview: Keep the cancel button enabled whenever possible. Hook up the escape key to cancel.

chrome/browser/resources/print_preview/print_header.js

Index: chrome/browser/resources/print_preview/print_header.js
===================================================================
--- chrome/browser/resources/print_preview/print_header.js	(revision 104750)
+++ chrome/browser/resources/print_preview/print_header.js	(working copy)
@@ -38,13 +38,16 @@
      */
     addEventListeners: function() {
       this.cancelButton_.onclick = function() {
-        chrome.send('closePrintPreviewTab');
+        cr.dispatchSimpleEvent(document, 'disableCancelButton');

[arv (Not doing code reviews), 2011/10/10 19:44:26]

It is a bit unclear why you are dispatching an event here. Can't you just call a
method or use a setter?

[Lei Zhang, 2011/10/10 20:03:14]

Done.

+        closePrintPreviewTab();
       };
       this.printButton_.onclick = this.onPrintButtonClicked_.bind(this);
       document.addEventListener('updateSummary',
                                 this.updateSummary_.bind(this));
       document.addEventListener('updatePrintButton',
                                 this.updatePrintButton_.bind(this));
+      document.addEventListener('disableCancelButton',
+                                this.disableCancelButton_.bind(this));
     },
 
     /**
@@ -58,10 +61,20 @@
         this.cancelButton_.classList.add('loading');
         this.summary_.innerHTML = localStrings.getString('printing');
       }
+      cr.dispatchSimpleEvent(document, 'disableCancelButton');
       requestToPrintDocument();
     },
 
     /**
+     * Disables the cancel button and removes its keydown event listener.
+     * @private
+     */
+    disableCancelButton_: function() {
+      window.removeEventListener('keydown');

[arv (Not doing code reviews), 2011/10/10 19:44:26]

This will not work. You need to pass in the function you added.

[dpapad, 2011/10/10 19:53:24]

Or you could add it as window.onkeydown = ....; and do window.onkeydown = null;
here.

[Lei Zhang, 2011/10/10 20:03:14]

Done.

+      this.cancelButton_.disabled = true;
+    },
+
+    /**
      * Updates the state of |this.printButton_| depending on the user selection.
      * The button is enabled only when the following conditions are true.
      * 1) The selected page ranges are valid.