Media Galleries API: hookup the AllGalleries permission and add tests.

chrome/test/data/extensions/api_test/media_galleries/experimental/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 experimentalMediaGalleries = chrome.experimental.mediaGalleries;
+
+var nullCallback = function(result) {
+  chrome.test.assertEq(null, result);
+};
+
+chrome.test.runTests([
+  function extractEmbeddedThumbnails() {
+    var result = experimentalMediaGalleries.extractEmbeddedThumbnails({});
+    chrome.test.assertEq(null, result);
+    chrome.test.succeed();
+  },
+
+  function assembleMediaFile() {
+    experimentalMediaGalleries.assembleMediaFile(
+        new Blob, {},
+        chrome.test.callbackPass(nullCallback));
+  },
+]);