Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/callback_work_item.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/installer/util/callback_work_item.h"
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "chrome/installer/util/work_item.h"
 
 CallbackWorkItem::CallbackWorkItem(
     base::Callback<bool(const CallbackWorkItem&)> callback)
     : callback_(callback),
       roll_state_(RS_UNDEFINED) {
 }
 
 CallbackWorkItem::~CallbackWorkItem() {
 }
 
-bool CallbackWorkItem::Do() {
+bool CallbackWorkItem::DoImpl() {
   DCHECK_EQ(roll_state_, RS_UNDEFINED);
 
   roll_state_ = RS_FORWARD;
   bool result = callback_.Run(*this);
   roll_state_ = RS_UNDEFINED;
 
   return result;
 }
 
-void CallbackWorkItem::Rollback() {
+void CallbackWorkItem::RollbackImpl() {
   DCHECK_EQ(roll_state_, RS_UNDEFINED);
 
   roll_state_ = RS_BACKWARD;
   ignore_result(callback_.Run(*this));
   roll_state_ = RS_UNDEFINED;
 }
 
 bool CallbackWorkItem::IsRollback() const {
   DCHECK_NE(roll_state_, RS_UNDEFINED);
   return roll_state_ == RS_BACKWARD;
 }