Fix more disabled MSVC warnings, base/ edition.

base/numerics/safe_math_impl.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 SAFE_MATH_IMPL_H_
 #define SAFE_MATH_IMPL_H_
 
 #include <stdint.h>
 
 #include <cmath>
@@ skipping 259 matching lines @@
       -static_cast<typename SignedIntegerForSize<T>::type>(value));
 }
 
 template <typename T>
 typename enable_if<
     std::numeric_limits<T>::is_integer&& std::numeric_limits<T>::is_signed,
     T>::type
 CheckedAbs(T value, RangeConstraint* validity) {
   *validity =
       value != std::numeric_limits<T>::min() ? RANGE_VALID : RANGE_OVERFLOW;
-  return std::abs(value);
+  return static_cast<T>(std::abs(value));
 }
 
 template <typename T>
 typename enable_if<
     std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed,
     T>::type
 CheckedAbs(T value, RangeConstraint* validity) {
   // Absolute value of a positive is just its identiy.
   *validity = RANGE_VALID;
   return value;
@@ skipping 61 matching lines @@
   RangeConstraint validity_;
 
  public:
   template <typename Src, NumericRepresentation type>
   friend class CheckedNumericState;
 
   CheckedNumericState() : value_(0), validity_(RANGE_VALID) {}
 
   template <typename Src>
   CheckedNumericState(Src value, RangeConstraint validity)
-      : value_(value),
+      : value_(static_cast<T>(value)),
         validity_(GetRangeConstraint(validity |
                                      DstRangeRelationToSrcRange<T>(value))) {
     COMPILE_ASSERT(std::numeric_limits<Src>::is_specialized,
                    argument_must_be_numeric);
   }
 
   // Copy constructor.
   template <typename Src>
   CheckedNumericState(const CheckedNumericState<Src>& rhs)
       : value_(static_cast<T>(rhs.value())),
@@ skipping 120 matching lines @@
                             sizeof(T) >= (2 * sizeof(Lhs)) &&
                             StaticDstRangeRelationToSrcRange<T, Rhs>::value !=
                                 NUMERIC_RANGE_CONTAINED &&
                             sizeof(T) >= (2 * sizeof(Rhs));
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // SAFE_MATH_IMPL_H_