Merge to XFA: Add namespace and-re-arrange PDFium's local copy of /base.

third_party/template_util.h

-// 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.
-
-#ifndef BASE_TEMPLATE_UTIL_H_
-#define BASE_TEMPLATE_UTIL_H_
-
-#include <cstddef>  // For size_t.
-
-namespace base {
-
-template<class T, T v>
-struct integral_constant {
-  static const T value = v;
-  typedef T value_type;
-  typedef integral_constant<T, v> type;
-};
-
-typedef integral_constant<bool, true> true_type;
-typedef integral_constant<bool, false> false_type;
-
-template <class T, class U> struct is_same : public false_type {};
-template <class T> struct is_same<T,T> : true_type {};
-
-template<bool B, class T = void>
-struct enable_if {};
-
-template<class T>
-struct enable_if<true, T> { typedef T type; };
-
-}  // namespace base
-
-#endif  // BASE_TEMPLATE_UTIL_H_