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

chrome/browser/wrench_menu_model.cc

Index: chrome/browser/wrench_menu_model.cc
diff --git a/chrome/browser/wrench_menu_model.cc b/chrome/browser/wrench_menu_model.cc
index c48b973e68ee7ec3e1b0fe360fdfedfb93ba704a..27d8e0994f2031517ebef36b0bc481660651b9e6 100644
--- a/chrome/browser/wrench_menu_model.cc
+++ b/chrome/browser/wrench_menu_model.cc
@@ -396,3 +396,9 @@ bool WrenchMenuModel::IsDynamicItem(int index) const {
   return command_id == IDC_SYNC_BOOKMARKS ||
          command_id == IDC_ABOUT;
 }
+
+bool WrenchMenuModel::IsCommandIdEnabled(int command_id) const {
+  if (delegate_)
+    return delegate_->IsCommandIdEnabled(command_id);
+  return true;
+}