switch mediaGalleries to .idl api definition

chrome/test/data/extensions/api_test/media_gallery/test.js

-// 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.
-
-var mediaGalleries = chrome.experimental.mediaGalleries;
-var mediaFileSystemsListCallback = function(results) {
-  // There should be a "Pictures" directory on all desktop platforms.
-  var expectedFileSystems = 1;
-  // But not on Android and ChromeOS.
-  if (/Android/.test(navigator.userAgent) || /CrOS/.test(navigator.userAgent)) {
-    expectedFileSystems = 0;
-  }
-  chrome.test.assertEq(expectedFileSystems, results.length);
-};
-var nullCallback = function(result) {
-  chrome.test.assertEq(null, result);
-};
-
-function runTests(tests) {
-  chrome.test.getConfig(function(config) {
-    operatingSystem = config.osName;
-    chrome.test.runTests(tests);
-  });
-}
-
-chrome.test.runTests([
-  function getGalleries() {
-    mediaGalleries.getMediaFileSystems(
-        chrome.test.callbackPass(mediaFileSystemsListCallback));
-  },
-
-  function openMediaGalleryManager() {
-    // Just confirm that the function exists.
-    chrome.test.assertTrue(mediaGalleries.openMediaGalleryManager !== null);
-    chrome.test.succeed()
-  },
-
-  function extractEmbeddedThumbnails() {
-    var result = mediaGalleries.extractEmbeddedThumbnails({});
-    chrome.test.assertEq(null, result);
-    chrome.test.succeed()
-  },
-
-  function assembleMediaFile() {
-    mediaGalleries.assembleMediaFile(
-        {}, {}, chrome.test.callbackPass(nullCallback));
-  },
-]);