This histogram is recorded only in content/browser/loader/resource_loader\.cc, which is not used when the network service is enabled.  We should figure out if we can just remove the histograms, or if we still need them.  If the latter is the case, we'll need to figure out how to hook them up when the NetworkService is enabled.

I don't believe that hooking up this histogram should block experimenting with the network service on Windows Canary.