Change platform app api getDisplayPath to take FileEntry.

chrome/renderer/resources/extensions/file_system_custom_bindings.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.
+
+// Custom bindings for the fileSystem API.
+
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
+
+chromeHidden.registerCustomHook('fileSystem', function(bindingsAPI) {
+  bindingsAPI.apiFunctions.setUpdateArgumentsPostValidate(
+      'getDisplayPath', function(fileEntry, callback) {
+    var fileSystemName = fileEntry.filesystem.name;
+    var relativePath = fileEntry.fullPath.slice(1);
+    return [fileSystemName, relativePath, callback];
+  });
+});