Revert 144807 - Rewrite DownloadsApiTest in C++.

chrome/test/data/extensions/api_test/downloads/test.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.
 
 // downloads api test
 // browser_tests.exe --gtest_filter=DownloadsApiTest.Downloads
 
 // Comment this out to enable debugging.
 console.debug = function() {};
 
@@ skipping 1080 matching lines @@
     },
 
     function callNotifyPass() {
       chrome.test.notifyPass();
       setTimeout(chrome.test.callback(function() {
         console.debug('');
       }), 0);
     }
   ]);
 });