Add namespace and re-arrange PDFium's local copy of chromium /base.

third_party/numerics/safe_conversions.h

-// Copyright 2014 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_SAFE_CONVERSIONS_H_
-#define BASE_SAFE_CONVERSIONS_H_
-
-#include <limits>
-
-#include "../logging.h"
-#include "safe_conversions_impl.h"
-
-namespace base {
-
-// Convenience function that returns true if the supplied value is in range
-// for the destination type.
-template <typename Dst, typename Src>
-inline bool IsValueInRangeForNumericType(Src value) {
-  return internal::DstRangeRelationToSrcRange<Dst>(value) ==
-         internal::RANGE_VALID;
-}
-
-// checked_cast<> is analogous to static_cast<> for numeric types,
-// except that it CHECKs that the specified numeric conversion will not
-// overflow or underflow. NaN source will always trigger a CHECK.
-template <typename Dst, typename Src>
-inline Dst checked_cast(Src value) {
-  CHECK(IsValueInRangeForNumericType<Dst>(value));
-  return static_cast<Dst>(value);
-}
-
-// saturated_cast<> is analogous to static_cast<> for numeric types, except
-// that the specified numeric conversion will saturate rather than overflow or
-// underflow. NaN assignment to an integral will trigger a CHECK condition.
-template <typename Dst, typename Src>
-inline Dst saturated_cast(Src value) {
-  // Optimization for floating point values, which already saturate.
-  if (std::numeric_limits<Dst>::is_iec559)
-    return static_cast<Dst>(value);
-
-  switch (internal::DstRangeRelationToSrcRange<Dst>(value)) {
-    case internal::RANGE_VALID:
-      return static_cast<Dst>(value);
-
-    case internal::RANGE_UNDERFLOW:
-      return std::numeric_limits<Dst>::min();
-
-    case internal::RANGE_OVERFLOW:
-      return std::numeric_limits<Dst>::max();
-
-    // Should fail only on attempting to assign NaN to a saturated integer.
-    case internal::RANGE_INVALID:
-      CHECK(false);
-      return std::numeric_limits<Dst>::max();
-  }
-
-  NOTREACHED();
-  return static_cast<Dst>(value);
-}
-
-}  // namespace base
-
-#endif  // BASE_SAFE_CONVERSIONS_H_
-