Take 2 at implementing activeTab.

chrome/browser/extensions/extension_tabs_module.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_EXTENSION_TABS_MODULE_H__
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_TABS_MODULE_H__
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 104 matching lines @@
   virtual bool RunImpl() OVERRIDE;
   DECLARE_EXTENSION_FUNCTION_NAME("tabs.highlight")
 };
 class UpdateTabFunction : public AsyncExtensionFunction {
  public:
   UpdateTabFunction();
 
  protected:
   virtual ~UpdateTabFunction() {}
   virtual bool UpdateURLIfPresent(base::DictionaryValue* update_props,
+                                  int tab_id,
                                   bool* is_async);
   virtual void PopulateResult();
 
   TabContentsWrapper* tab_contents_;
 
  private:
   virtual bool RunImpl() OVERRIDE;
   void OnExecuteCodeFinished(bool success,
                              int32 page_id,
                              const std::string& error);
@@ skipping 57 matching lines @@
   // The format (JPEG vs PNG) of the resulting image.  Set in RunImpl().
   ImageFormat image_format_;
 
   // Quality setting to use when encoding jpegs.  Set in RunImpl().
   int image_quality_;
 
   DECLARE_EXTENSION_FUNCTION_NAME("tabs.captureVisibleTab")
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_TABS_MODULE_H__