Take 2 at implementing activeTab.

chrome/browser/extensions/extension_tabs_module.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/extension_tabs_module.h"
 
 #include <algorithm>
 #include <limits>
 #include <vector>
 
@@ skipping 1176 matching lines @@
   }
 
   tab_contents_ = contents;
 
   // TODO(rafaelw): handle setting remaining tab properties:
   // -title
   // -favIconUrl
 
   // Navigate the tab to a new location if the url is different.
   bool is_async = false;
-  if (!UpdateURLIfPresent(update_props, &is_async))
+  if (!UpdateURLIfPresent(update_props, tab_id, &is_async))
     return false;
 
   bool active = false;
   // TODO(rafaelw): Setting |active| from js doesn't make much sense.
   // Move tab selection management up to window.
   if (update_props->HasKey(keys::kSelectedKey))
     EXTENSION_FUNCTION_VALIDATE(update_props->GetBoolean(
         keys::kSelectedKey, &active));
 
   // The 'active' property has replaced 'selected'.
@@ skipping 43 matching lines @@
   }
 
   if (!is_async) {
     PopulateResult();
     SendResponse(true);
   }
   return true;
 }
 
 bool UpdateTabFunction::UpdateURLIfPresent(DictionaryValue* update_props,
+                                           int tab_id,
                                            bool* is_async) {
   if (!update_props->HasKey(keys::kUrlKey))
     return true;
 
   std::string url_string;
   EXTENSION_FUNCTION_VALIDATE(update_props->GetString(
       keys::kUrlKey, &url_string));
   GURL url = ExtensionTabUtil::ResolvePossiblyRelativeURL(
       url_string, GetExtension());
 
   if (!url.is_valid()) {
     error_ = ExtensionErrorUtils::FormatErrorMessage(
         keys::kInvalidUrlError, url_string);
     return false;
   }
 
   // Don't let the extension crash the browser or renderers.
   if (ExtensionTabUtil::IsCrashURL(url)) {
     error_ = keys::kNoCrashBrowserError;
     return false;
   }
 
   // JavaScript URLs can do the same kinds of things as cross-origin XHR, so
   // we need to check host permissions before allowing them.
   if (url.SchemeIs(chrome::kJavaScriptScheme)) {
     if (!GetExtension()->CanExecuteScriptOnPage(
-            tab_contents_->web_contents()->GetURL(), NULL, &error_)) {
+            tab_contents_->web_contents()->GetURL(), tab_id, NULL, &error_)) {
       return false;
     }
 
     tab_contents_->extension_tab_helper()->script_executor()->ExecuteScript(
         extension_id(),
         ScriptExecutor::JAVASCRIPT,
         url.path(),
         ScriptExecutor::TOP_FRAME,
         UserScript::DOCUMENT_IDLE,
         ScriptExecutor::MAIN_WORLD,
@@ skipping 292 matching lines @@
 
     if (options->HasKey(keys::kQualityKey)) {
       EXTENSION_FUNCTION_VALIDATE(
           options->GetInteger(keys::kQualityKey, &image_quality_));
     }
   }
 
   // captureVisibleTab() can return an image containing sensitive information
   // that the browser would otherwise protect.  Ensure the extension has
   // permission to do this.
-  if (!GetExtension()->CanCaptureVisiblePage(web_contents->GetURL(), &error_))
+  if (!GetExtension()->CanCaptureVisiblePage(
+        web_contents->GetURL(),
+        wrapper->extension_tab_helper()->GetTabId(),
+        &error_)) {
     return false;
+  }
 
   RenderViewHost* render_view_host = web_contents->GetRenderViewHost();
   content::RenderWidgetHostView* view = render_view_host->GetView();
   if (!view) {
     error_ = keys::kInternalVisibleTabCaptureError;
     return false;
   }
   skia::PlatformCanvas* temp_canvas = new skia::PlatformCanvas;
   render_view_host->CopyFromBackingStore(
       gfx::Rect(),
@@ skipping 172 matching lines @@
   // called for every API call the extension made.
   GotLanguage(language);
 }
 
 void DetectTabLanguageFunction::GotLanguage(const std::string& language) {
   result_.reset(Value::CreateStringValue(language.c_str()));
   SendResponse(true);
 
   Release();  // Balanced in Run()
 }