Replace uses of hash_map in //base

base/files/file_path.h

 // 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.
 
 // FilePath is a container for pathnames stored in a platform's native string
 // type, providing containers for manipulation in according with the
 // platform's conventions for pathnames.  It supports the following path
 // types:
 //
 //                   POSIX            Windows
@@ skipping 92 matching lines @@
 #define BASE_FILES_FILE_PATH_H_
 
 #include <stddef.h>
 
 #include <iosfwd>
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/compiler_specific.h"
-#include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_piece.h"
 #include "build/build_config.h"
 
 // Windows-style drive letter support and pathname separator characters can be
 // enabled and disabled independently, to aid testing.  These #defines are
 // here so that the same setting can be used in both the implementation and
 // in the unit test.
 #if defined(OS_WIN)
@@ skipping 339 matching lines @@
 // Macros for string literal initialization of FilePath::CharType[], and for
 // using a FilePath::CharType[] in a printf-style format string.
 #if defined(OS_POSIX)
 #define FILE_PATH_LITERAL(x) x
 #define PRFilePath "s"
 #elif defined(OS_WIN)
 #define FILE_PATH_LITERAL(x) L ## x
 #define PRFilePath "ls"
 #endif  // OS_WIN
 
-// Provide a hash function so that hash_sets and maps can contain FilePath
-// objects.
-namespace BASE_HASH_NAMESPACE {
+namespace std {
 
-template<>
+template <>
 struct hash<base::FilePath> {
-  size_t operator()(const base::FilePath& f) const {
+  typedef base::FilePath argument_type;
+  typedef std::size_t result_type;
+  result_type operator()(argument_type const& f) const {
     return hash<base::FilePath::StringType>()(f.value());
   }
 };
 
-}  // namespace BASE_HASH_NAMESPACE
+}  // namespace std
 
 #endif  // BASE_FILES_FILE_PATH_H_