Introduce a file-manager-new-ui flag for the new UI of Files.app.

chrome/browser/resources/file_manager/js/background.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.
 
 'use strict';
 
 /**
  * Map of all currently open app window. The key is an app id.
  */
 var appWindows = {};
@@ skipping 225 matching lines @@
 /**
  * @return {Object} File manager window create options.
  */
 function createFileManagerOptions() {
   return {
     defaultLeft: Math.round(window.screen.availWidth * 0.1),
     defaultTop: Math.round(window.screen.availHeight * 0.1),
     defaultWidth: Math.round(window.screen.availWidth * 0.8),
     defaultHeight: Math.round(window.screen.availHeight * 0.8),
     minWidth: 320,
-    minHeight: 240
+    minHeight: 240,
+    frame: util.platform.newUI() ? 'none' : 'chrome'
   };
 }
 
 /**
  * @param {Object=} opt_appState App state.
  * @param {number=} opt_id Window id.
  */
 function launchFileManager(opt_appState, opt_id) {
   var id = opt_id || nextFileManagerWindowID;
   nextFileManagerWindowID = Math.max(nextFileManagerWindowID, id + 1);
@@ skipping 141 matching lines @@
 function addExecuteHandler() {
   if (!chrome.fileBrowserHandler) {
     console.log('Running outside Chrome OS, loading mock API implementations.');
     util.loadScripts(['js/mock_chrome.js'], addExecuteHandler);
     return;
   }
   chrome.fileBrowserHandler.onExecute.addListener(executeFileBrowserTask);
 }
 
 addExecuteHandler();