Revert of Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/copy_tree_work_item.h

Index: chrome/installer/util/copy_tree_work_item.h
diff --git a/chrome/installer/util/copy_tree_work_item.h b/chrome/installer/util/copy_tree_work_item.h
index dbfdfcc24ad34a0695af6a35a1d15749767edc0a..9aa426a95fca9c948f4aeb1493150c61d127b65d 100644
--- a/chrome/installer/util/copy_tree_work_item.h
+++ b/chrome/installer/util/copy_tree_work_item.h
@@ -27,6 +27,10 @@
  public:
   ~CopyTreeWorkItem() override;
 
+  bool Do() override;
+
+  void Rollback() override;
+
  private:
   friend class WorkItem;
 
@@ -40,10 +44,6 @@
                    const base::FilePath& temp_dir,
                    CopyOverWriteOption overwrite_option,
                    const base::FilePath& alternative_path);
-
-  // WorkItem:
-  bool DoImpl() override;
-  void RollbackImpl() override;
 
   // Checks if the path specified is in use (and hence can not be deleted)
   bool IsFileInUse(const base::FilePath& path);