wstring: use a few more FilePaths to remove Hack functions

chrome/installer/util/work_item.cc

 // 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.
 
 #include "chrome/installer/util/work_item.h"
 
 #include "chrome/installer/util/conditional_work_item_list.h"
 #include "chrome/installer/util/copy_tree_work_item.h"
 #include "chrome/installer/util/create_dir_work_item.h"
 #include "chrome/installer/util/create_reg_key_work_item.h"
 #include "chrome/installer/util/delete_tree_work_item.h"
 #include "chrome/installer/util/delete_reg_key_work_item.h"
 #include "chrome/installer/util/delete_reg_value_work_item.h"
 #include "chrome/installer/util/move_tree_work_item.h"
 #include "chrome/installer/util/self_reg_work_item.h"
 #include "chrome/installer/util/set_reg_value_work_item.h"
 #include "chrome/installer/util/work_item_list.h"
 
 WorkItem::WorkItem() : ignore_failure_(false) {
 }
 
 WorkItem::~WorkItem() {
 }
 
 CopyTreeWorkItem* WorkItem::CreateCopyTreeWorkItem(
-    const std::wstring& source_path,
-    const std::wstring& dest_path,
-    const std::wstring& temp_dir,
+    const FilePath& source_path,
+    const FilePath& dest_path,
+    const FilePath& temp_dir,
     CopyOverWriteOption overwrite_option,
-    const std::wstring& alternative_path) {
+    const FilePath& alternative_path) {
   return new CopyTreeWorkItem(source_path, dest_path, temp_dir,
                               overwrite_option, alternative_path);
 }
 
 CreateDirWorkItem* WorkItem::CreateCreateDirWorkItem(const FilePath& path) {
   return new CreateDirWorkItem(path);
 }
 
 CreateRegKeyWorkItem* WorkItem::CreateCreateRegKeyWorkItem(
     HKEY predefined_root, const std::wstring& path) {
@@ skipping 65 matching lines @@
 }
 
 // static
 WorkItemList* WorkItem::CreateNoRollbackWorkItemList() {
   return new NoRollbackWorkItemList();
 }
 
 WorkItemList* WorkItem::CreateConditionalWorkItemList(Condition* condition) {
   return new ConditionalWorkItemList(condition);
 }