Functionality has been requested in the Extension API for Javascript to...

chrome/renderer/extensions/extension_api_client_unittest.cc

 // Copyright (c) 2009 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 "base/file_util.h"
 #include "base/path_service.h"
 #include "base/string_util.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/renderer/extensions/extension_process_bindings.h"
@@ skipping 404 matching lines @@
                "Uncaught Error: Invalid value for argument 1. "
                "Expected 'function' but got 'integer'.");
 
   ExpectJsPass("chrome.tabs.remove(2, function(){})",
                "RemoveTab", "2");
 
   ExpectJsPass("chrome.tabs.remove(2)",
                "RemoveTab", "2");
 }
 
+TEST_F(ExtensionAPIClientTest, GetVisibleTabCapture) {
+  ExpectJsFail("chrome.tabs.getVisibleTabCapture(0);",
+               "Uncaught Error: Parameter 1 is required.");
+
+  ExpectJsFail("chrome.tabs.getVisibleTabCapture(function(){}, 0)",
+               "Uncaught Error: Invalid value for argument 0. "
+               "Expected 'integer' but got 'function'.");
+
+  ExpectJsPass("chrome.tabs.getVisibleTabCapture(null, function(img){});",
+               "GetVisibleTabCapture", "null");
+}
+
 // Bookmark API tests
 // TODO(erikkay) add more variations here
 
 TEST_F(ExtensionAPIClientTest, CreateBookmark) {
   ExpectJsFail(
       "chrome.bookmarks.create({parentId:'x', title:0}, function(){})",
       "Uncaught Error: Invalid value for argument 0. "
       "Property 'parentId': Expected 'integer' but got 'string', "
       "Property 'title': Expected 'string' but got 'integer'.");
 
@@ skipping 76 matching lines @@
                "EnablePageAction",
                "[\"dummy\",{\"tabId\":0,\"url\":\"http://foo/\","
                            "\"title\":\"a\",\"iconId\":0}]");
 
   // Now try disablePageAction.
   ExpectJsPass("chrome.pageActions.disableForTab("
                "\"dummy\", {tabId: 0, url: \"http://foo/\"});",
                "DisablePageAction",
                "[\"dummy\",{\"tabId\":0,\"url\":\"http://foo/\"}]");
 }