2064855 - urlbar.zeroprefix.* counts the new search bar and the smartbar too

Status: RESOLVED FIXED

(Firefox :: Address Bar, defect, P2)

Description

[Dão Gottwald [:dao]]

The three urlbar.zeroprefix.* counters live in UrlbarView: close() derives isShowingZeroPrefix from the query context alone (this.#queryContext && !this.#queryContext.searchString), and onQueryFinished() records the exposure on !queryContext.searchString. Neither looks at which input owns the view, and UrlbarInputBase gives every <moz-urlbar> its own UrlbarView — so #searchbar-new counts into these, and so does the smartbar, which constructs its own view.

This looks like drift rather than a decision. The counters came in with bug 1806765 (January 2023), when the address bar was the only consumer of the view. #searchbar-new arrived in bug 1975009 (August 2025) and reused the element without revisiting them.

The documented meaning is still address-bar-only. browser/components/urlbar/docs/telemetry.md describes the zero-prefix view as "the view that's shown when the user clicks in the urlbar before typing a search string", often called the "top sites" view. All three are expires: never with legacy mirrors URLBAR_ZEROPREFIX_{ABANDONMENT,ENGAGEMENT,EXPOSURE}, so this is what long-running dashboards read.

Nothing catches the blending: browser/components/urlbar/tests/browser-telemetry/browser_zeroPrefix.js drives only the address bar.

Suggested fix: gate the three sites on the address bar, the way the switcher's urlbar.unifiedsearchbutton.* counters already are (sapName == "urlbar"), and add search bar coverage to the test. If blending is wanted instead, these probes need a surface dimension and the docs need to say so.

Bug 2062209 puts <moz-urlbar> on about:newtab, which would add a third contributor to the same numbers.

Comment 1

[Dão Gottwald [:dao]]

Attachment: Bug 2064855 - Count only the address bar's zero-prefix view. r?Standard8!

#searchbar-new and the smartbar have counted into these since they started sharing the view, which nobody revisited when the address bar stopped being its only consumer.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/46fac315452d
https://hg.mozilla.org/integration/autoland/rev/59659613cce2
Count only the address bar's zero-prefix view. r=Standard8

Comment 3

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/59659613cce2