[Extensions Page] Add a listener on extension list for "hasExtensions" changing

chrome/browser/resources/extensions/extensions.js

Index: chrome/browser/resources/extensions/extensions.js
diff --git a/chrome/browser/resources/extensions/extensions.js b/chrome/browser/resources/extensions/extensions.js
index 06b62379a5112d70932832ca49299da59d6b61a3..73729c46c76b1d28ea47f432d6417dcd1df711ea 100644
--- a/chrome/browser/resources/extensions/extensions.js
+++ b/chrome/browser/resources/extensions/extensions.js
@@ -274,11 +274,15 @@ cr.define('extensions', function() {
           document.documentElement.classList.remove('loading');
         }, 0);
 
-        /** @const */
-        var hasExtensions = extensionList.getNumExtensions() != 0;
-        $('no-extensions').hidden = hasExtensions;
-        $('extension-list-wrapper').hidden = !hasExtensions;
-        $('extension-settings-list').updateFocusableElements();
+        var onHasExtensionsChanged = function() {

[Dan Beam, 2015/04/23 18:01:39]

onExtensionChanged (or at the very least HaveExtensions or HasExtension, right
now this makes little sense...)

[Devlin, 2015/04/23 18:27:31]

How about onExtensionCountChanged?  (Before, it was saying that the property
'hasExtensions' on the list has changed, not that the extensions themselves have
changed.  But yes, it was very weirdly phrased.)

+          /** @const */
+          var hasExtensions = extensionList.getNumExtensions() != 0;
+          $('no-extensions').hidden = hasExtensions;
+          $('extension-list-wrapper').hidden = !hasExtensions;
+          $('extension-settings-list').updateFocusableElements();
+        };

[Dan Beam, 2015/04/23 18:01:38]

make this a permanent instance or static method instead of this weird dance
you're doing

[Devlin, 2015/04/23 18:27:31]

Done.

+        extensionList.onHasExtensionsChanged = onHasExtensionsChanged;
+        onHasExtensionsChanged();
       }.bind(this));
     },