Bug 1064217 - Fix closed window list for menu bar of hidden window on OS X r=gijs

browser/base/content/browser-places.js

@@ -504,12 +504,21 @@ function HistoryMenu(aPopupShowingEvent) {
 }
 
 HistoryMenu.prototype = {
+  _getClosedTabCount() {
+    // SessionStore doesn't track the hidden window, so just return zero then.
+    if (window == Services.appShell.hiddenDOMWindow) {
+      return 0;
+    }
+
+    return SessionStore.getClosedTabCount(window);
+  },
+
   toggleRecentlyClosedTabs: function HM_toggleRecentlyClosedTabs() {
     // enable/disable the Recently Closed Tabs sub menu
     var undoMenu = this._rootElt.getElementsByClassName("recentlyClosedTabsMenu")[0];
 
     // no restorable tabs, so disable menu
-    if (SessionStore.getClosedTabCount(window) == 0)
+    if (this._getClosedTabCount() == 0)
       undoMenu.setAttribute("disabled", true);
     else
       undoMenu.removeAttribute("disabled");
@@ -527,7 +536,7 @@ HistoryMenu.prototype = {
       undoPopup.removeChild(undoPopup.firstChild);
 
     // no restorable tabs, so make sure menu is disabled, and return
-    if (SessionStore.getClosedTabCount(window) == 0) {
+    if (this._getClosedTabCount() == 0) {
       undoMenu.setAttribute("disabled", true);
       return;
     }