Where: infra/appengine/findit/common/chromium_deps.py

In GetChromeDependency we locally define a recursive function FlattenDepTree. It looks like DEPS never gets very deep, so we don't have to worry about stack overflow issues; but, there might still be performance benefits to refactoring this function to be non-recursive (i.e., to build up a work queue as needed).

If this ever looks to be a bottleneck, or if someone's just looking for something to do, this might be worth exploring.