[Files.app] Fix a potential error in ShareDialog/FileManagerBrowserTest

chrome/test/data/chromeos/file_manager/share_dialog_mock/main.js

 // 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.
 
 // Namespace for the share dialog mock.
 var shareDialog = {};
 
 /**
  * Origin of Files.app.
  * @type {string}
@@ skipping 75 matching lines @@
  * done.
  * @private
  */
 shareDialog.onResizeComplete_ = function() {
   var container = document.querySelector('#container');
   container.style.width = shareDialog.TARGET_WIDTH + 'px';
   container.style.height = shareDialog.TARGET_HEIGHT + 'px';
 };
 
 /**
+ * Changes the visibility of the dialog.
+ * @param {boolean} visible True to set the dialog visible, false to set it
+ *     invisible.
+ */
+shareDialog.setVisible = function(visible) {
+  shareDialog.sendMessage_('setVisible', {visible: visible});
+};
+
+/**
  * Prepares the embedder to make the contents visible.
  */
 shareDialog.prepareForVisible = function() {
   shareDialog.sendMessage_('prepareForVisible');
 };
 
 /**
  * Resizes the embedder to the content window dimensions.
  */
 shareDialog.resize = function() {
@@ skipping 40 matching lines @@
 
 /**
  * Initializes the mocked share dialog.
  */
 shareDialog.initialize = function() {
   window.addEventListener('message', shareDialog.onMessage_);
   shareDialog.prepareForVisible();
 };
 
 window.addEventListener('load', shareDialog.initialize);