[WebUI] Make drag'n'drop future proof.

chrome/browser/resources/net_internals/import_view.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.
 
 /**
  * This view displays options for importing data from a log file.
  */
 var ImportView = (function() {
   'use strict';
 
@@ skipping 62 matching lines @@
     },
 
     /**
      * Called when something is dragged over the drop target.
      *
      * Returns false to cancel default browser behavior when a single file is
      * being dragged.  When this happens, we may not receive a list of files for
      * security reasons, which is why we allow the |files| array to be empty.
      */
     onDrag: function(event) {
-      return !event.dataTransfer.types.contains('Files') ||
+      // NOTE: Use Array.prototype.indexOf here is necessary while WebKit
+      // decides which type of data structure dataTransfer.types will be
+      // (currently between DOMStringList and Array). These have different APIs
+      // so assuming one type or the other was breaking things. See
+      // http://crbug.com/115433. TODO(dbeam): Remove when standardized more.
+      var indexOf = Array.prototype.indexOf;
+      return indexOf.call(event.dataTransfer.types, 'Files') == -1 ||
              event.dataTransfer.files.length > 1;
     },
 
     /**
      * Called when something is dropped onto the drop target.  If it's a single
      * file, tries to load it as a log file.
      */
     onDrop: function(event) {
-      if (!event.dataTransfer.types.contains('Files') ||
+      var indexOf = Array.prototype.indexOf;
+      if (indexOf.call(event.dataTransfer.types, 'Files') == -1 ||
           event.dataTransfer.files.length != 1) {
         return;
       }
       event.preventDefault();
 
       // Loading a log file may hide the currently active tab.  Switch to the
       // import tab to prevent this.
       document.location.hash = 'import';
 
       this.loadLogFile(event.dataTransfer.files[0]);
@@ skipping 109 matching lines @@
       this.loadedInfoOsType_.innerText = ClientInfo.os_type;
       this.loadedInfoCommandLine_.innerText = ClientInfo.command_line;
 
       // User comments will not be available when dumped from command line.
       this.loadedInfoUserComments_.innerText = userComments || '';
     }
   };
 
   return ImportView;
 })();