Fixes for re-enabling more MSVC level 4 warnings: misc edition #2

extensions/common/id_util.cc

 // Copyright (c) 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.
 
 #include "extensions/common/id_util.h"
 
 #include "base/files/file_path.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "crypto/sha2.h"
@@ skipping 42 matching lines @@
   return GenerateId(path_bytes);
 }
 
 base::FilePath MaybeNormalizePath(const base::FilePath& path) {
 #if defined(OS_WIN)
   // Normalize any drive letter to upper-case. We do this for consistency with
   // net_utils::FilePathToFileURL(), which does the same thing, to make string
   // comparisons simpler.
   base::FilePath::StringType path_str = path.value();
   if (path_str.size() >= 2 && path_str[0] >= L'a' && path_str[0] <= L'z' &&
-      path_str[1] == ':')
-    path_str[0] += ('A' - 'a');
+      path_str[1] == L':')
+    path_str[0] = towupper(path_str[0]);
 
   return base::FilePath(path_str);
 #else
   return path;
 #endif
 }
 
 }  // namespace id_util
 }  // namespace extensions