Entries in enums.xml should be kept when removing a feature flag

[Morten Stenshorne]

Hi, I'm currently on code health rotation, looking into removal of stale
base::Feature flags. I went through some recently landed CLs, and see
that that quite a few, when removing a base::Feature flag, also remove
the corresponding entries from tools/metrics/histograms/enums.xml

However:

https://source.chromium.org/chromium/chromium/src/+/main:tools/metrics/histograms/enums.xml;l=8172-8173;drc=ec87e233bc04a96e2a4675eaae072d4579ab737b

"Don't remove entries when removing a flag; they are still used to
decode data from previous Chrome versions."

I don't know exactly what damage such removal does. Does anybody care?
If yes, there's cleanup cleanup work to be done.

--
Morten Stenshorne, Software developer,
Blink/Layout, Google, Oslo, Norway

[Reilly Grant]

The relevant part of the histogram documentation: https://chromium.googlesource.com/chromium/src/+/lkgr/tools/metrics/histograms/README.md#obsolete

It's okay to remove a <histogram> or <enum> entirely but don't remove individual <int> entries if the <enum> itself is being kept. 

Reilly Grant | Software Engineer | rei...@chromium.org | Google Chrome

--
--
Chromium Developers mailing list: chromi...@chromium.org
View archives, change email options, or unsubscribe:
    http://groups.google.com/a/chromium.org/group/chromium-dev
---
You received this message because you are subscribed to the Google Groups "Chromium-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email to chromium-dev...@chromium.org.
To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/chromium-dev/874ivlixf9.fsf%40bro.lan.