Affected versions

• Firefox 90.0a1 (BuildId:20210512174859)
• Firefox 89.0b11 (BuildId:20210511190154)

Affected platforms

• Windows 10 64bit.
• macOS 10.15
• Ubuntu 20.04

Steps to reproduce

1. Launch Firefox.
2. Access the about:telemetry page.
3. Right click on the Tab Bar (not on a tab).
4. Click the “New Tab” option.
5. Switch to the about:telemetry page and refresh it.
6. Perform a search for a newtab event.

Expected result

• Telemetry events are recorded successfully.

Actual result

• No telemetry event is recorded for the "New Tab" action.

Regression Range

• Not sure if this is a regression. I can reproduce this issue with builds from 2021-04-12 (when bug 1692840 landed).

Notes

• As a side note, Triggering the “New Tab” context menu option from a particular tab successfully records a telemetry event called “context-openANewTab”.

Ni? Gijs as per slack request.

Rather than adding a new scalar I'm just filing the toolbar context menu's tab-related items
under the tab context menu. The use of other items - customization options like
showing/hiding toolbars and adding/removing buttons - are already covered by other event
telemetry, and this will help group similar items together.

https://hg.mozilla.org/mozilla-central/rev/42756cd62fb9

Verified that New Tab option from Tab bar context menu now records data under toolbar-context-openANewTab using latest Nightlty across platforms (Windows 10, Ubuntu 18.04 and macOS 11.3).