Looks like we do basic fileio here in the content process during init. Depending on the path this might be failing silently. No assertion, no return value, and the debug output goes to stderr on Windows. So if it does fail, no one would know.
At the moment gfxWindowsPlatform::GetPlatformCMSOutputProfile appears to always be called as part of ContentChild::RecvSetXPCOMProcessAttributes, which is currently before we lower the sandbox and it should be working fine. However, we should probably have assertions or use gfxDevCrash or something in this code, depending on how serious we think a failure is. Clearing the priority in the hope that it gets back into a triage.