Tabs API is usable without tabs permission.

chrome/renderer/extensions/dispatcher.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/renderer/extensions/dispatcher.h"
 
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_piece.h"
@@ skipping 1045 matching lines @@
     DLOG(ERROR) << "Not in a v8::Context";
     return false;
   }
 
   if (!context->extension()) {
     v8::ThrowException(
         v8::Exception::Error(v8::String::New("Not in an extension.")));
     return false;
   }
 
-  // We need to whitelist tabs.executeScript and tabs.insertCSS because they
-  // are granted under special circumstances with the activeTab permission
-  // (note that the browser checks too, so this isn't a security problem).
-  //
-  // Only the browser knows which tab this call will be sent to... sometimes we
-  // *could* figure it out (if the extension gives an explicit tab ID in the
-  // call), but the expected case will be the extension passing through -1,
-  // meaning the active tab, and only the browser safely knows what this is.
-  bool skip_permission_check = (function_name == "tabs.executeScript") ||
-                               (function_name == "tabs.insertCSS");
-
-  if (!skip_permission_check &&
-      !context->extension()->HasAPIPermission(function_name)) {
+  if (!context->extension()->HasAPIPermission(function_name)) {
     static const char kMessage[] =
         "You do not have permission to use '%s'. Be sure to declare"
         " in your manifest what permissions you need.";
     std::string error_msg = base::StringPrintf(kMessage, function_name.c_str());
     v8::ThrowException(
         v8::Exception::Error(v8::String::New(error_msg.c_str())));
     return false;
   }
 
   if (ExtensionAPI::GetSharedInstance()->IsPrivileged(function_name) &&
@@ skipping 12 matching lines @@
   // we should abort.
   WebKit::WebFrame* frame = context->web_frame();
   ExtensionURLInfo url_info(frame->document().securityOrigin(),
       UserScriptSlave::GetDataSourceURLForFrame(frame));
   CHECK(!extensions_.IsSandboxedPage(url_info));
 
   return true;
 }
 
 }  // namespace extensions