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

base/string_util_win.h

Index: base/string_util_win.h
diff --git a/base/string_util_win.h b/base/string_util_win.h
index 8836f7442299c2252444cf4a2fb830deb1620538..d1addb03fa2da5db9fe015ec2da879f6467afe0f 100644
--- a/base/string_util_win.h
+++ b/base/string_util_win.h
@@ -35,9 +35,12 @@ inline int strncmp16(const char16* s1, const char16* s2, size_t 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;
 }
 
@@ -45,9 +48,12 @@ 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;
 }