Revert of Delete old files after an update.

chrome/installer/util/delete_old_versions.h

Index: chrome/installer/util/delete_old_versions.h
diff --git a/chrome/installer/util/delete_old_versions.h b/chrome/installer/util/delete_old_versions.h
deleted file mode 100644
index 098119b6611a62e8d8a6cb20fb3d2e7836a91a23..0000000000000000000000000000000000000000
--- a/chrome/installer/util/delete_old_versions.h
+++ /dev/null
@@ -1,24 +0,0 @@
-// 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_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_
-#define CHROME_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_
-
-class WorkItemList;
-
-namespace installer {
-
-class InstallerState;
-
-// Adds to |work_item_list| a WorkItem which deletes files that belong to old
-// versions of Chrome. chrome.exe, new_chrome.exe and their associated version
-// directories are never deleted. Also, no file is deleted for a given version
-// if a .exe or .dll file for that version is in use. |installer_state| must be
-// alive when |work_item_list| is executed.
-void AddDeleteOldVersionsWorkItem(const InstallerState& installer_state,
-                                  WorkItemList* work_item_list);
-
-}  // namespace installer
-
-#endif  // CHROME_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_