Add new danger type for uncommon or unknown downloads.

chrome/browser/resources/chromeos/active_downloads.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.
 
 /**
  * Wrapper for chrome.send.
  */
 function chromeSend(func, arg) {
   if (arg == undefined)
     arg = '';
@@ skipping 317 matching lines @@
       return;
 
     this.dangerous = createChild('div', 'dangerousprompt', this.rowbutton);
 
     // Handle dangerous files, extensions and dangerous urls.
     var dangerText;
     if (dangerType == 'DANGEROUS_URL') {
       dangerText = localStrings.getString('dangerousurl');
     } else if (dangerType == 'DANGEROUS_CONTENT') {
       dangerText = localStrings.getStringF('dangerouscontent', this.name);
+    } else if (dangerType == 'UNCOMMON_CONTENT') {
+      dangerText = localStrings.getStringF('uncommoncontent', this.name);
     } else if (dangerType == 'DANGEROUS_FILE' && this.path.match(/\.crx$/)) {
       dangerText = localStrings.getString('dangerousextension');
     } else {
       dangerText = localStrings.getStringF('dangerousfile', this.name);
     }
     createChild('span', 'dangerousprompttext', this.dangerous, dangerText);
 
     var self = this;
     createChild('span', 'confirm', this.dangerous,
         localStrings.getString('discard'),
@@ skipping 276 matching lines @@
   update: function(result) {
     var row = this.getRow(result.file_path);
     if (!row && !DiscardResult(result))
       row = new DownloadRow(this, result);
 
     row && row.update(result);
   },
 };
 
 document.addEventListener('DOMContentLoaded', init);