There are so few users with this configuration that we need to stop
sampling in order to get data. Sampling is still in effect for
"baseline" users with the feature disabled.
We use separate schemas to simplify analytics on the two populations.
Bug: T214493
Change-Id: I16e4ed236e50e1e246ff28ff0dba3e52e4b56caf
Collect EventLogging metrics for footnote and reference link
interactions, so that we can compare behavior with and without
Reference Previews enabled.
This tracking will be reverted once analysis is complete.
A mostly arbitrary sample rate of 1/1000 is hardcoded here. This is
loosely based on the latest tuning of Popups sampling at 1/100,
divided by a conservative factor of 10 to ensure headroom.
The sample is skewed by skipping clients without sendBeacon support,
but we're avoiding the mw.track synchronous fallback, which injects an
image tag and introduces lag any time the user clicks external links
in the references.
Bug: T231529
Change-Id: Iad32b64114f88675eecbb01712418c968e3cf661
