Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/create_dir_work_item.h

Index: chrome/installer/util/create_dir_work_item.h
diff --git a/chrome/installer/util/create_dir_work_item.h b/chrome/installer/util/create_dir_work_item.h
index 217196d1e1e063c9f77892dd898eb34fb49b0829..d0718d19c7681ba371407ad6bbfee416c27a3d04 100644
--- a/chrome/installer/util/create_dir_work_item.h
+++ b/chrome/installer/util/create_dir_work_item.h
@@ -16,18 +16,19 @@ class CreateDirWorkItem : public WorkItem {
  public:
   ~CreateDirWorkItem() override;
 
-  bool Do() override;
+ private:
+  friend class WorkItem;
+
+  explicit CreateDirWorkItem(const base::FilePath& path);
+
+  // WorkItem:
+  bool DoImpl() override;
 
   // Rollback tries to remove all directories created along the path.
   // If the leaf directory or one of the intermediate directories are not
   // empty, the non-empty directory and its parent directories will not be
   // removed.
-  void Rollback() override;
-
- private:
-  friend class WorkItem;
-
-  explicit CreateDirWorkItem(const base::FilePath& path);
+  void RollbackImpl() override;
 
   // Get the top most directory that needs to be created in order to create
   // "path_", and set "top_path_" accordingly. if "path_" already exists,