Fix more disabled MSVC warnings, base/ edition.

base/strings/string_util.h

 // Copyright 2013 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.
 //
 // This file defines utility functions for working with strings.
 
 #ifndef BASE_STRINGS_STRING_UTIL_H_
 #define BASE_STRINGS_STRING_UTIL_H_
 
 #include <ctype.h>
@@ skipping 334 matching lines @@
 }
 
 template <typename Char>
 inline bool IsHexDigit(Char c) {
   return (c >= '0' && c <= '9') ||
          (c >= 'A' && c <= 'F') ||
          (c >= 'a' && c <= 'f');
 }
 
 template <typename Char>
-inline Char HexDigitToInt(Char c) {
+inline char HexDigitToInt(Char c) {
   DCHECK(IsHexDigit(c));
   if (c >= '0' && c <= '9')
-    return c - '0';
+    return static_cast<char>(c - '0');
   if (c >= 'A' && c <= 'F')
-    return c - 'A' + 10;
+    return static_cast<char>(c - 'A' + 10);
   if (c >= 'a' && c <= 'f')
-    return c - 'a' + 10;
+    return static_cast<char>(c - 'a' + 10);
   return 0;
 }
 
 // Returns true if it's a whitespace character.
 inline bool IsWhitespace(wchar_t c) {
   return wcschr(base::kWhitespaceWide, c) != NULL;
 }
 
 // Return a byte string in human-readable format with a unit suffix. Not
 // appropriate for use in any UI; use of FormatBytes and friends in ui/base is
@@ skipping 141 matching lines @@
 #elif defined(WCHAR_T_IS_UTF32)
   typedef uint32 Unsigned;
 #endif
 };
 template<>
 struct ToUnsigned<short> {
   typedef unsigned short Unsigned;
 };
 
 #endif  // BASE_STRINGS_STRING_UTIL_H_