The Mac wrench menu zoom controls honor the global enabled state of the zoom commands.

chrome/browser/cocoa/wrench_menu_controller.mm

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/cocoa/wrench_menu_controller.h"
 
 #include "app/menus/menu_model.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/app/chrome_dll_resource.h"
 #include "chrome/browser/browser.h"
@@ skipping 56 matching lines @@
   if (![menu delegate]) {
     [menu setDelegate:self];
   }
   return menu;
 }
 
 - (void)menuWillOpen:(NSMenu*)menu {
   NSString* title = base::SysUTF16ToNSString(
       [self wrenchMenuModel]->GetLabelForCommandId(IDC_ZOOM_PERCENT_DISPLAY));
   [[zoomItem_ viewWithTag:IDC_ZOOM_PERCENT_DISPLAY] setTitle:title];
+  bool plusEnabled = [self wrenchMenuModel]->IsCommandIdEnabled(IDC_ZOOM_PLUS);
+  bool minusEnabled = [self wrenchMenuModel]->IsCommandIdEnabled(
+      IDC_ZOOM_MINUS);
+
+  [zoomPlus_ setEnabled:plusEnabled];
+  [zoomMinus_ setEnabled:minusEnabled];
 
   NSImage* icon = [self wrenchMenuModel]->browser()->window()->IsFullscreen() ?
       [NSImage imageNamed:NSImageNameExitFullScreenTemplate] :
           [NSImage imageNamed:NSImageNameEnterFullScreenTemplate];
   [zoomFullScreen_ setImage:icon];
 }
 
 // Used to dispatch commands from the Wrench menu. The custom items within the
 // menu cannot be hooked up directly to First Responder because the window in
 // which the controls reside is not the BrowserWindowController, but a
@@ skipping 49 matching lines @@
   // of the segmented control.
   itemFrame.size.width += resizeAmount;
   [editItem_ setFrame:itemFrame];
 
   // Keep the spacing between the right edges of the menu and the control.
   controlFrame.origin.x = NSWidth(itemFrame) - edge - NSWidth(controlFrame);
   [editControl_ setFrame:controlFrame];
 }
 
 @end  // @implementation WrenchMenuController