Enable positional parameters for base::vsnprintf and base::vswprintf on Windows.

base/string_util_win.h

 // Copyright (c) 2006-2008 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_STRING_UTIL_WIN_H_
 #define BASE_STRING_UTIL_WIN_H_
 #pragma once
 
 #include <stdarg.h>
 #include <stdio.h>
@@ skipping 17 matching lines @@
 inline int strncasecmp(const char* s1, const char* s2, size_t count) {
   return _strnicmp(s1, s2, count);
 }
 
 inline int strncmp16(const char16* s1, const char16* s2, size_t count) {
   return ::wcsncmp(s1, s2, count);
 }
 
 inline int vsnprintf(char* buffer, size_t size,
                      const char* format, va_list arguments) {
-  int length = vsnprintf_s(buffer, size, size - 1, format, arguments);
-  if (length < 0)
-    return _vscprintf(format, arguments);
+  int length = _vsprintf_p(buffer, size, format, arguments);
+  if (length < 0) {
+    if (size > 0)
+      buffer[0] = 0;
+    return _vscprintf_p(format, arguments);
+  }
   return length;
 }
 
 inline int vswprintf(wchar_t* buffer, size_t size,
                      const wchar_t* format, va_list arguments) {
   DCHECK(IsWprintfFormatPortable(format));
 
-  int length = _vsnwprintf_s(buffer, size, size - 1, format, arguments);
-  if (length < 0)
-    return _vscwprintf(format, arguments);
+  int length = _vswprintf_p(buffer, size, format, arguments);
+  if (length < 0) {
+    if (size > 0)
+      buffer[0] = 0;
+    return _vscwprintf_p(format, arguments);
+  }
   return length;
 }
 
 }  // namespace base
 
 #endif  // BASE_STRING_UTIL_WIN_H_