Add support for persistent file access in apps.

chrome/test/data/extensions/api_test/file_system/restore_entry/test.js

Index: chrome/test/data/extensions/api_test/file_system/restore_entry/test.js
diff --git a/chrome/test/data/extensions/api_test/file_system/restore_entry/test.js b/chrome/test/data/extensions/api_test/file_system/restore_entry/test.js
new file mode 100644
index 0000000000000000000000000000000000000000..ff1e66f35df45a7179c826dfed1d06b80997c104
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/file_system/restore_entry/test.js
@@ -0,0 +1,27 @@
+// Copyright 2013 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.
+
+chrome.test.runTests([
+  function restoreEntryWorks() {
+    var id = 'magic id';
+    chrome.fileSystem.isRestorable(id, chrome.test.callbackPass(
+        function(isRestorable) {
+      chrome.test.assertTrue(isRestorable);
+    }));
+    chrome.fileSystem.restoreEntry(id, chrome.test.callbackPass(
+        function(restoredEntry) {
+      chrome.test.assertTrue(restoredEntry != null);
+      chrome.test.assertEq(
+          chrome.fileSystem.retainEntry(restoredEntry), id);
+      checkEntry(restoredEntry, 'writable.txt', false /* isNew */,
+                 true /*shouldBeWritable */);
+      }));
+    chrome.fileSystem.isRestorable('wrong id', chrome.test.callbackPass(
+        function(isRestorable) {
+      chrome.test.assertFalse(isRestorable);
+    }));
+    chrome.fileSystem.restoreEntry('wrong id', chrome.test.callbackFail(
+        'Unknown id'));
+  }
+]);