Add best-effort/allow rollback flags on WorkItem.

chrome/installer/util/self_reg_work_item.h

Index: chrome/installer/util/self_reg_work_item.h
diff --git a/chrome/installer/util/self_reg_work_item.h b/chrome/installer/util/self_reg_work_item.h
index 544621cf3844918bcd03f7fe6c654fd8d04aa992..5f3a3d4d922424608be8f923bba54f3ee196f958 100644
--- a/chrome/installer/util/self_reg_work_item.h
+++ b/chrome/installer/util/self_reg_work_item.h
@@ -15,9 +15,6 @@ class SelfRegWorkItem : public WorkItem {
  public:
   ~SelfRegWorkItem() override;
 
-  bool Do() override;
-  void Rollback() override;
-
  private:
   friend class WorkItem;
 
@@ -32,6 +29,10 @@ class SelfRegWorkItem : public WorkItem {
   SelfRegWorkItem(const std::wstring& dll_path, bool do_register,
                   bool user_level_registration);
 
+  // WorkItem:
+  bool DoImpl() override;
+  void RollbackImpl() override;
+
   // Examines the DLL at dll_path looking for either DllRegisterServer (if
   // do_register is true) or DllUnregisterServer (if do_register is false).
   // Returns true if the DLL exports the function and it a call to it