Tabs API is usable without tabs permission.

chrome/browser/extensions/menu_manager.cc

Index: chrome/browser/extensions/menu_manager.cc
diff --git a/chrome/browser/extensions/menu_manager.cc b/chrome/browser/extensions/menu_manager.cc
index 9e29835393017c08436e27a6680804e6c361bcb9..aea883daba9f37b4a2b85f64e2ef15997ac31b83 100644
--- a/chrome/browser/extensions/menu_manager.cc
+++ b/chrome/browser/extensions/menu_manager.cc
@@ -643,8 +643,8 @@ void MenuManager::ExecuteCommand(Profile* profile,
   // No tab info in a platform app.
   if (!extension || !extension->is_platform_app()) {
     // Note: web_contents only NULL in unit tests :(
-    if (web_contents)
-      args->Append(ExtensionTabUtil::CreateTabValue(web_contents));
+    if (web_contents && extension)
+      args->Append(ExtensionTabUtil::CreateTabValue(web_contents, extension));
     else
       args->Append(new DictionaryValue());
   }