Errors while deleting old version dirs no longer cause them to grow in odd ways.

chrome/installer/util/delete_tree_work_item.h

 // Copyright (c) 2011 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_TREE_WORK_ITEM_H_
 #define CHROME_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 35 matching lines @@
   // performed only if none of the key files are in use.
   scoped_array<FilePath> key_paths_;
 
   // Contains the temp directories for the backed-up key files. The directories
   // are created and populated in Do() as-needed. We don't use a standard
   // container for this since ScopedTempDir isn't CopyConstructible.
   scoped_array<ScopedTempDir> key_backup_paths_;
 
   // The temporary directory into which the original root_path_ has been moved.
   ScopedTempDir backup_path_;
+
+  // Set to true once root_path_ has been copied into backup_path_.
+  bool copied_to_backup_;
 };
 
 #endif  // CHROME_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H_