Removes downgrade browser test hack and verifies renamed user data dir.

chrome/browser/downgrade/user_data_downgrade.h

 // Copyright 2016 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.
 
 #ifndef CHROME_BROWSER_DOWNGRADE_USER_DATA_DOWNGRADE_H_
 #define CHROME_BROWSER_DOWNGRADE_USER_DATA_DOWNGRADE_H_
 
 #include "base/files/file_path.h"
 #include "base/version.h"
 
@@ skipping 20 matching lines @@
 base::Version GetLastVersion(const base::FilePath& user_data_dir);
 
 // Schedules a search for the removal of any directories moved aside by
 // MoveUserDataForFirstRunAfterDowngrade. This operation is idempotent,
 // and may be safely called when no such directories exist.
 void DeleteMovedUserDataSoon();
 
 // Returns true if Chrome is installed by MSI.
 bool IsMSIInstall();
 
-// Changes the behavior of the above functions to simulate a downgrade for use
-// in tests. MoveUserDataForFirstRunAfterDowngrade will no longer rely on
-// registry and DeleteMovedUserDataSoon will always post task into blocking
-// pool for brower test.
-void SetSimulateDowngradeForTest(bool is_browser_test);
-
 }  // namespace downgrade
 
 #endif  // CHROME_BROWSER_DOWNGRADE_USER_DATA_DOWNGRADE_H_