Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/delete_reg_value_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_REG_VALUE_WORK_ITEM_H_
 #define CHROME_INSTALLER_UTIL_DELETE_REG_VALUE_WORK_ITEM_H_
 
 #include <windows.h>
 
 #include <string>
 
 #include "chrome/installer/util/work_item.h"
 
 // A WorkItem subclass that deletes a registry value with REG_SZ, REG_DWORD, or
 // REG_QWORD type at the specified path. The value is only deleted if the target
 // key exists.
 class DeleteRegValueWorkItem : public WorkItem {
  public:
   ~DeleteRegValueWorkItem() override;
 
-  bool Do() override;
-
-  void Rollback() override;
-
  private:
   friend class WorkItem;
 
   enum DeletionStatus {
     // The status before Do is called.
     DELETE_VALUE,
     // One possible outcome after Do(). Value is deleted.
     VALUE_DELETED,
     // One possible outcome after Do(). Value is not found.
     VALUE_NOT_FOUND,
     // The status after Do() and Rollback() is called.
     VALUE_ROLLED_BACK,
     // Another possible outcome after Do() (when there is an error).
     VALUE_UNCHANGED
   };
 
   DeleteRegValueWorkItem(HKEY predefined_root,
                          const std::wstring& key_path,
                          REGSAM wow64_acccess,
                          const std::wstring& value_name);
 
+  // WorkItem:
+  bool DoImpl() override;
+  void RollbackImpl() override;
+
   // Root key of the target key under which the value is set. The root key can
   // only be one of the predefined keys on Windows.
   HKEY predefined_root_;
 
   // Path of the target key under which the value is set.
   std::wstring key_path_;
 
   // Name of the value to be set.
   std::wstring value_name_;
 
   // Whether to force 32-bit or 64-bit view of the target key.
   REGSAM wow64_access_;
 
   DeletionStatus status_;
 
   // Previous value.
   DWORD previous_type_;
   std::string previous_value_;
 };
 
 #endif  // CHROME_INSTALLER_UTIL_DELETE_REG_VALUE_WORK_ITEM_H_