message: Fixing a minor casting issue that MSVC is complaining about
diff: @@ -51,7 +51,7 @@ public:
  }
  void WriteString(const string &val) {
  - Write<uint32_t>(val.size());
  + Write<uint32_t>((uint32_t)val.size());
  if (val.size() > 0) {
  PotentialResize(val.size());
  