AbsolutePath should probably also work on non-Windows platforms.

base/file_util.cc

 // Copyright (c) 2006-2008 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 "base/file_util.h"
 
 #include <stdio.h>
 
 #include <fstream>
 
@@ skipping 280 matching lines @@
 
 bool CloseFile(FILE* file) {
   if (file == NULL)
     return true;
   return fclose(file) == 0;
 }
 
 // Deprecated functions ----------------------------------------------------
 
 bool AbsolutePath(std::wstring* path_str) {
-  FilePath path(*path_str);
+  FilePath path(FilePath::FromWStringHack(*path_str));
   if (!AbsolutePath(&path))
     return false;
   *path_str = path.ToWStringHack();
   return true;
 }
 bool Delete(const std::wstring& path, bool recursive) {
   return Delete(FilePath::FromWStringHack(path), recursive);
 }
 bool Move(const std::wstring& from_path, const std::wstring& to_path) {
   return Move(FilePath::FromWStringHack(from_path),
@@ skipping 33 matching lines @@
 bool GetTempDir(std::wstring* path_str) {
   FilePath path;
   if (!GetTempDir(&path))
     return false;
   *path_str = path.ToWStringHack();
   return true;
 }
 
 }  // namespace