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

chrome/installer/util/callback_work_item.h

Index: chrome/installer/util/callback_work_item.h
diff --git a/chrome/installer/util/callback_work_item.h b/chrome/installer/util/callback_work_item.h
index bcfd56c8833caefa4bcc3cde1723693544c19129..3cc22f656ed415a4c1453444d0bffe700ba76b8c 100644
--- a/chrome/installer/util/callback_work_item.h
+++ b/chrome/installer/util/callback_work_item.h
@@ -35,6 +35,9 @@
  public:
   ~CallbackWorkItem() override;
 
+  bool Do() override;
+  void Rollback() override;
+
   bool IsRollback() const;
 
  private:
@@ -46,12 +49,7 @@
     RS_BACKWARD,
   };
 
-  explicit CallbackWorkItem(
-      base::Callback<bool(const CallbackWorkItem&)> callback);
-
-  // WorkItem:
-  bool DoImpl() override;
-  void RollbackImpl() override;
+  CallbackWorkItem(base::Callback<bool(const CallbackWorkItem&)> callback);
 
   base::Callback<bool(const CallbackWorkItem&)> callback_;
   RollState roll_state_;