Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/delete_tree_work_item.h

Index: chrome/installer/util/delete_tree_work_item.h
diff --git a/chrome/installer/util/delete_tree_work_item.h b/chrome/installer/util/delete_tree_work_item.h
index 9af8fdf05079e770cbca6720634c384b7b6156cf..9f82103a2ca8f80963b2aa7080544390d9b232a9 100644
--- a/chrome/installer/util/delete_tree_work_item.h
+++ b/chrome/installer/util/delete_tree_work_item.h
@@ -23,10 +23,6 @@ class DeleteTreeWorkItem : public WorkItem {
  public:
   ~DeleteTreeWorkItem() override;
 
-  bool Do() override;
-
-  void Rollback() override;
-
  private:
   friend class WorkItem;
 
@@ -38,6 +34,10 @@ class DeleteTreeWorkItem : public WorkItem {
                      const base::FilePath& temp_path,
                      const std::vector<base::FilePath>& key_paths);

[fdoray, 2016/05/02 20:10:01]

|key_paths| is always empty. Can I remove the argument and all associated code?

[grt (UTC plus 2), 2016/05/06 18:39:13]

That'd be great. Unused code is just weight. We can add it back from history in
the future if needed.

[fdoray, 2016/05/10 18:35:28]

Done.

 
+  // WorkItem:
+  bool DoImpl() override;
+  void RollbackImpl() override;
+
   // Return temporary path for work based on |backup_path_| and |root_path_|.
   base::FilePath GetBackupPath();