The LocateEndOfHeaders and LocateEndOfAdditionalHeaders will as a result of https://chromium-review.googlesource.com/c/chromium/src/+/1396136 take in a size_t for buf_len and i, resolving truncation issues in many places.
Since an index is returned from these methods, the return value should also be a size_t. However, currently the method returns -1 if a marker is not found. Thus converting it to a size_t will require using something like std::string::npos instead and converting all places where -1 is currently used.