Added menuItem icon support, and little API for menu modification.

chrome/browser/resources/shared/js/cr/ui/menu_item.js

Index: chrome/browser/resources/shared/js/cr/ui/menu_item.js
diff --git a/chrome/browser/resources/shared/js/cr/ui/menu_item.js b/chrome/browser/resources/shared/js/cr/ui/menu_item.js
index 667d2f0c539ce26fb77acad8cb6176b70f950248..5b1ce65338d05bef1bbb0ee05db8631a7ad74026 100644
--- a/chrome/browser/resources/shared/js/cr/ui/menu_item.js
+++ b/chrome/browser/resources/shared/js/cr/ui/menu_item.js
@@ -39,6 +39,10 @@ cr.define('cr.ui', function() {
       // Adding the 'custom-appearance' class prevents widgets.css from changing
       // the appearance of this element.
       this.classList.add('custom-appearance');
+
+      var iconUrl;
+      if ((iconUrl = this.getAttribute('icon')))
+        this.iconUrl = iconUrl;

[James Hawkins, 2012/05/16 17:12:18]

Why not:

this.iconUrl = this.getAttribute('icon');

?

[Dmitry Zvorygin, 2012/05/17 12:11:15]

We don't want to set iconUrl to 'undefined'. Just leave default if iconUrl isn't
specified.

     },
 
     /**
@@ -92,6 +96,17 @@ cr.define('cr.ui', function() {
     },
 
     /**
+     * Menu icon.
+     * @type {string}
+     */
+    get iconUrl() {
+      return this.style.backgroundImage;
+    },
+    set iconUrl(url) {
+      this.style.backgroundImage = 'url(' + url + ')';
+    },
+
+    /**
      * @return {boolean} Whether the menu item is a separator.
      */
     isSeparator: function() {