Looking at the histograms, it seems that typically sum of samples in DataUse.MessageSize.NotTagged histogram is more than 50% of the sum of samples in DataUse.TrafficSize.System.Downstream.Foreground.NotCellular. That means at least 50% of the data used by services is unaccounted for.
We should add TAGS for all services, and in future add a DCHECK to ensure that all services attach the TAG when creating a network fetcher.
Comment 1 by rajendrant@chromium.org
, Oct 14 2016