Add FilePath to base namespace.

webkit/fileapi/file_system_file_util.cc

 // Copyright (c) 2012 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 "webkit/fileapi/file_system_file_util.h"
 
 namespace fileapi {
 
-FilePath FileSystemFileUtil::EmptyFileEnumerator::Next() {
-  return FilePath();
+base::FilePath FileSystemFileUtil::EmptyFileEnumerator::Next() {
+  return base::FilePath();
 }
 
 int64 FileSystemFileUtil::EmptyFileEnumerator::Size() {
   return 0;
 }
 
 base::Time FileSystemFileUtil::EmptyFileEnumerator::LastModifiedTime() {
   return base::Time();
 }
 
 bool FileSystemFileUtil::EmptyFileEnumerator::IsDirectory() {
   return false;
 }
 
 }  // namespace fileapi