Introduce a SetRegValueWorkItem overload that accepts a callback instead (...)

chrome/installer/util/work_item.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Base class for managing an action of a sequence of actions to be carried
 // out during install/update/uninstall. Supports rollback of actions if this
 // process fails.
 
 #ifndef CHROME_INSTALLER_UTIL_WORK_ITEM_H_
 #define CHROME_INSTALLER_UTIL_WORK_ITEM_H_
@@ skipping 19 matching lines @@
 class WorkItemList;
 
 namespace base {
 class FilePath;
 }
 
 // A base class that defines APIs to perform/rollback an action or a
 // sequence of actions during install/update/uninstall.
 class WorkItem {
  public:
+  // A callback that returns the desired value based on the |existing_value|.
+  // |existing_value| will be empty if the value didn't previously exist or
+  // existed under a non-string type.
+  using GetValueFromExistingCallback =
+      base::Callback<std::wstring(const std::wstring& existing_value)>;
+
   // All registry operations can be instructed to operate on a specific view
   // of the registry by specifying a REGSAM value to the wow64_access parameter.
   // The wow64_access parameter can be one of:
   // KEY_WOW64_32KEY - Operate on the 32-bit view.
   // KEY_WOW64_64KEY - Operate on the 64-bit view.
   // kWow64Default   - Operate on the default view (e.g. 32-bit on 32-bit
   //                   systems, and 64-bit on 64-bit systems).
   // See http://msdn.microsoft.com/en-us/library/windows/desktop/aa384129.aspx
   static const REGSAM kWow64Default = 0;
   // Possible states
@@ skipping 101 matching lines @@
   // Create a SetRegValueWorkItem that sets a registry value with REG_QWORD type
   // at the key with specified path.
   static SetRegValueWorkItem* CreateSetRegValueWorkItem(
       HKEY predefined_root,
       const std::wstring& key_path,
       REGSAM wow64_access,
       const std::wstring& value_name,
       int64 value_data,
       bool overwrite);
 
+  // Create a SetRegValueWorkItem that sets a registry value based on the value
+  // provided by |get_value_callback| given the existing value under
+  // |key_path\value_name|.
+  static SetRegValueWorkItem* CreateSetRegValueWorkItem(
+      HKEY predefined_root,
+      const std::wstring& key_path,
+      REGSAM wow64_access,
+      const std::wstring& value_name,
+      const GetValueFromExistingCallback& get_value_callback);
+
   // Add a SelfRegWorkItem that registers or unregisters a DLL at the
   // specified path.
   static SelfRegWorkItem* CreateSelfRegWorkItem(const std::wstring& dll_path,
                                                 bool do_register,
                                                 bool user_level_registration);
 
   // Create an empty WorkItemList. A WorkItemList can recursively contains
   // a list of WorkItems.
   static WorkItemList* CreateWorkItemList();
 
@@ skipping 43 matching lines @@
   WorkItem();
 
   // Specifies whether this work item my fail to complete and yet still
   // return true from Do().
   bool ignore_failure_;
 
   std::string log_message_;
 };
 
 #endif  // CHROME_INSTALLER_UTIL_WORK_ITEM_H_