Tabs API is usable without tabs permission.

chrome/browser/extensions/event_router.cc

 // 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.
 
 #include "chrome/browser/extensions/event_router.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/message_loop.h"
 #include "base/values.h"
@@ skipping 505 matching lines @@
   if (host->extension() && host->extension()->has_lazy_background_page())
     pm->DecrementLazyKeepaliveCount(host->extension());
 }
 
 void EventRouter::DispatchPendingEvent(const linked_ptr<Event>& event,
                                        ExtensionHost* host) {
   if (!host)
     return;
 
   if (listeners_.HasProcessListener(host->render_process_host(),
-                                    host->extension()->id()))
+                                    host->extension()->id())) {
     DispatchEventToProcess(host->extension()->id(),
                            host->render_process_host(), event);
+  }
 }
 
 void EventRouter::Observe(int type,
                           const content::NotificationSource& source,
                           const content::NotificationDetails& details) {
   switch (type) {
     case content::NOTIFICATION_RENDERER_PROCESS_TERMINATED:
     case content::NOTIFICATION_RENDERER_PROCESS_CLOSED: {
       content::RenderProcessHost* renderer =
           content::Source<content::RenderProcessHost>(source).ptr();
@@ skipping 63 matching lines @@
       event_args(event_args.Pass()),
       event_url(event_url),
       restrict_to_profile(restrict_to_profile),
       cross_incognito_args(NULL),
       user_gesture(user_gesture),
       info(info) {}
 
 Event::~Event() {}
 
 }  // namespace extensions