wstring: use a few more FilePaths to remove Hack functions

chrome/installer/util/work_item_list.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_list.h"
 
 #include "base/logging.h"
 #include "base/file_path.h"
 #include "chrome/installer/util/logging_installer.h"
 #include "chrome/installer/util/copy_tree_work_item.h"
@@ skipping 60 matching lines @@
   DCHECK(status_ == ADD_ITEM);
   list_.push_back(work_item);
 }
 
 WorkItem* WorkItemList::AddCopyTreeWorkItem(
     const std::wstring& source_path,
     const std::wstring& dest_path,
     const std::wstring& temp_dir,
     CopyOverWriteOption overwrite_option,
     const std::wstring& alternative_path) {
-  WorkItem* item = WorkItem::CreateCopyTreeWorkItem(source_path,
-                                                    dest_path,
-                                                    temp_dir,
+  WorkItem* item = WorkItem::CreateCopyTreeWorkItem(FilePath(source_path),
+                                                    FilePath(dest_path),
+                                                    FilePath(temp_dir),
                                                     overwrite_option,
-                                                    alternative_path);
+                                                    FilePath(alternative_path));
   AddWorkItem(item);
   return item;
 }
 
 WorkItem* WorkItemList::AddCreateDirWorkItem(const FilePath& path) {
   WorkItem* item = WorkItem::CreateCreateDirWorkItem(path);
   AddWorkItem(item);
   return item;
 }
 
@@ skipping 116 matching lines @@
     VLOG(1) << "NoRollbackWorkItemList: list execution succeeded";
 
   status_ = LIST_EXECUTED;
   return result;
 }
 
 void NoRollbackWorkItemList::Rollback() {
   NOTREACHED() << "Can't rollback a NoRollbackWorkItemList";
 }