Woah, thanks for flagging this Florian. Just to make sure I understand: right now, our denominator (Profile.NumberOfProfiles) is counting total profiles, but our numerators (Profile.NumberOfSignedInProfiles, Profiles.NumberOfProfilesWithAuthErrors, etc.) are counting only *active* profiles? So all of these rates are *lower* than they are in reality?

Eli: you're understanding it right.

😱 Fixing this seems important :) Luckily, for A/B tests, at least what we're doing is apples-to-apples.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/defcedc9d83d2e4dd9443c83a4191ace7445ed58

commit defcedc9d83d2e4dd9443c83a4191ace7445ed58
Author: Florian Uunk <feuunk@chromium.org>
Date: Thu Apr 26 11:56:06 2018

Create Profile.NumberOfActiveProfiles metric

Currently most Profile.NumberOf[...] metrics only count 28DA profiles.
However, the Profile.NumberOfProfiles metric counts all profiles,
including inactive ones.

Add a Profile.NumberOfActiveProfiles metric to use as denominator for
NumberOf[...] metrics that count active profiles. Also update the
documentation on the NumberOf[...] metrics to describe whether they
count all or only active profiles.

BUG= 832005 

Change-Id: I85a23dfd792e8a39a88459b989e911126a9fca48
Reviewed-on: https://chromium-review.googlesource.com/1021813
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: anthonyvd <anthonyvd@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Florian Uunk <feuunk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553986}
[modify] https://crrev.com/defcedc9d83d2e4dd9443c83a4191ace7445ed58/chrome/browser/profiles/profile_metrics.cc
[modify] https://crrev.com/defcedc9d83d2e4dd9443c83a4191ace7445ed58/components/profile_metrics/counts.cc
[modify] https://crrev.com/defcedc9d83d2e4dd9443c83a4191ace7445ed58/components/profile_metrics/counts.h
[modify] https://crrev.com/defcedc9d83d2e4dd9443c83a4191ace7445ed58/tools/metrics/histograms/histograms.xml