Quoting upstream [1]:

*This change makes me sad.*

*We intentionally minimize the work done in PreSandbox, not only for security,
but also because the cost is paid at process-startup time.*

The only problem I see with this patch is exactly what the first reviewer upstream also noticed. My first comment on this patch was also about this same concern.

So if any decision is pending on me, it is a no go, for the reasons I've been stating here over and over.

[1] https://codereview.chromium.org/15955009/#msg3