When testing the spawning of a Sandboxed process on windows 7, we found out that there is a function on BrokerServicesBase (https://cs.chromium.org/chromium/src/sandbox/win/src/broker_services.cc?sq=package:chromium&l=303) that returns a SBOX_ERROR_GENERIC under certain circumstances.

The function that returns this error code is MakeTokens defined in PolicyBase (https://cs.chromium.org/chromium/src/sandbox/win/src/sandbox_policy_base.cc?dr=CSs&l=429) However it fails to recover the last error code from the operating system, which makes the error code rather useless. 

It would be ideal if the MakeTokens could return an error other than SBOX_ERROR_GENERIC and/or recover the operating system's error code.