Force COM machinery to notice that the path to the DelegateExecute verb handler has changed.

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() {
+  DCHECK_EQ(roll_state_, RS_UNDEFINED);
+
+  roll_state_ = RS_FORWARD;
+  bool result = callback_.Run(*this);
+  roll_state_ = RS_UNDEFINED;

[robertshield, 2012/08/30 17:52:43]

Should we leave roll_state_ set to RS_FORWARD, which would allow us to alter the
DCHECK in Rollback to ensure that Do() has first been called?

[grt (UTC plus 2), 2012/08/30 18:21:50]

Discussed in person: doing so would make the DCHECK in IsRollback not work,
which I think is more valuable.  Although I could add new state to detect
Rollback called before Do, it doesn't seem worth it since this would really be
enforcing behavior of WorkItemList, which should be tested independently.

+
+  return result;
+}
+
+void CallbackWorkItem::Rollback() {
+  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;
+}