Tabs API is usable without tabs permission.

chrome/browser/extensions/browser_event_router.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_BROWSER_EVENT_ROUTER_H_
 #define CHROME_BROWSER_EXTENSIONS_BROWSER_EVENT_ROUTER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 109 matching lines @@
       Profile* profile,
       const char* event_name,
       scoped_ptr<base::ListValue> event_args,
       scoped_ptr<base::ListValue> cross_incognito_args);
 
   void DispatchEventWithTab(Profile* profile,
                             const std::string& extension_id,
                             const char* event_name,
                             const content::WebContents* web_contents,
                             bool active,
-                            EventRouter::UserGestureState user_gesture);
+                            EventRouter::UserGestureState user_gesture,
+                            scoped_ptr<ListValue> event_args);
+
+  // DispatchEvent with a tab value appended as the last argument.
+  void DispatchEventWithTab(Profile* profile,
+                            const std::string& extension_id,
+                            const char* event_name,
+                            const content::WebContents* web_contents,
+                            bool active,
+                            EventRouter::UserGestureState user_gesture) {
+    DispatchEventWithTab(profile, extension_id, event_name, web_contents,
+                         active, user_gesture,
+                         scoped_ptr<ListValue>(new ListValue).Pass());
+  }
 
   void DispatchSimpleBrowserEvent(Profile* profile,
                                   const int window_id,
                                   const char* event_name);
 
   // Packages |changed_properties| as a tab updated event for the tab |contents|
   // and dispatches the event to the extension.
   void DispatchTabUpdatedEvent(content::WebContents* contents,
                                DictionaryValue* changed_properties);
 
@@ skipping 71 matching lines @@
 
   // The main profile that owns this event router.
   Profile* profile_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserEventRouter);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_BROWSER_EVENT_ROUTER_H_