Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/conditional_work_item_list.h

Index: chrome/installer/util/conditional_work_item_list.h
diff --git a/chrome/installer/util/conditional_work_item_list.h b/chrome/installer/util/conditional_work_item_list.h
index 834b1e0df66bdafefb0774cf8962bed6fea69b58..ba28ca2b83e3e7e08742a5658580a7d41cb1885c 100644
--- a/chrome/installer/util/conditional_work_item_list.h
+++ b/chrome/installer/util/conditional_work_item_list.h
@@ -17,15 +17,17 @@ class ConditionalWorkItemList : public WorkItemList {
   explicit ConditionalWorkItemList(Condition* condition);
   ~ConditionalWorkItemList() override;
 
+ private:
+  // WorkItemList:
+
   // If condition_->ShouldRun() returns true, then execute the items in this
   // list and return true iff they all succeed. If condition_->ShouldRun()
   // returns false, does nothing and returns true.
-  bool Do() override;
+  bool DoImpl() override;
 
   // Does a rollback of the items (if any) that were run in Do.
-  void Rollback() override;
+  void RollbackImpl() override;
 
- protected:
   // Pointer to a Condition that is used to determine whether to run this
   // WorkItemList.
   std::unique_ptr<Condition> condition_;