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

chrome/test/data/extensions/api_test/media_galleries/read_access/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.mediaGalleries;
+
+var mediaFileSystemsDirectoryErrorCallback = function(err) {
+  chrome.test.fail("Couldn't read from directory: " + err);
+};
+
+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);
+  if (expectedFileSystems) {
+    var dir_reader = results[0].root.createReader();
+    dir_reader.readEntries(chrome.test.callbackPass(),
+                           mediaFileSystemsDirectoryErrorCallback);
+  }
+};
+
+chrome.test.runTests([
+  function getGalleries() {
+    mediaGalleries.getMediaFileSystems(
+        chrome.test.callbackPass(mediaFileSystemsListCallback));
+  },
+]);