2009673 - Add comments capturing why the description and status fields are not required for the processExited telemetry in ApplicationExitInfoMetrics

Status: NEW

(Firefox for Android :: Experimentation and Telemetry, enhancement)

Description

[twhite]

Add a clarifying comment noting that the description and status fields are intentionally excluded, based on data from a previous implementation.

Key info from Kaya in https://phabricator.services.mozilla.com/D277428:

I've added and then removed the description a while ago. It is not super descriptive in my opinion. The reason I added that was to get more insights into the OTHER process exit resons and why they were happening. In general, I could not justify the cost of having description field. Manufacturers had different descriptions and numbering system for their custom logs, and not all of them were well-versed. So, aggregation is not possible with this field. IMHO, it is not a very useful field to have.
See prev efforts: https://bugzilla.mozilla.org/show_bug.cgi?id=1909108. And removing here: https://bugzilla.mozilla.org/show_bug.cgi?id=1925362#c0.

When it comes to status, I did not care much about the SIGNALED process exits that's why it did not have much use for me.
My main goal when capturing this metric was to mainly focus on tab reloading reasons (nothing a user has control over - when OS kills the child processes due to mainly the low_memory and excessive_resource usage. Crashes and ANRs are also good to have, but not much actionable from this metric and we have much better tools to diagnose those two.).

Here's the query I made for the descriptions for REASON_OTHER kills when I introduced the filed and before I removed it: https://sql.telemetry.mozilla.org/queries/101722/source
My points above and in my previous comment were based on the outcome of this query.