Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/set_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_SET_REG_VALUE_WORK_ITEM_H__
 #define CHROME_INSTALLER_UTIL_SET_REG_VALUE_WORK_ITEM_H__
 
 #include <windows.h>
 #include <stdint.h>
 
@@ skipping 31 matching lines @@
 
   // Implies |overwrite_| and TYPE_SZ for now.
   SetRegValueWorkItem(HKEY predefined_root,
                       const std::wstring& key_path,
                       REGSAM wow64_access,
                       const std::wstring& value_name,
                       const GetValueFromExistingCallback& get_value_callback);
 
   ~SetRegValueWorkItem() override;
 
-  bool Do() override;
-
-  void Rollback() override;
-
  private:
   enum SettingStatus {
     // The status before Do is called.
     SET_VALUE,
     // One possible outcome after Do(). A new value is created under the key.
     NEW_VALUE_CREATED,
     // One possible outcome after Do(). The previous value under the key has
     // been overwritten.
     VALUE_OVERWRITTEN,
     // One possible outcome after Do(). No change is applied, either
     // because we are not allowed to overwrite the previous value, or due to
     // some errors like the key does not exist.
     VALUE_UNCHANGED,
     // The status after Do and Rollback is called.
     VALUE_ROLL_BACK
   };
 
+  // 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_;
 
@@ skipping 10 matching lines @@
   // Type of data to store
   DWORD type_;
   std::vector<uint8_t> value_;
   DWORD previous_type_;
   std::vector<uint8_t> previous_value_;
 
   SettingStatus status_;
 };
 
 #endif  // CHROME_INSTALLER_UTIL_SET_REG_VALUE_WORK_ITEM_H__