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Today’s meeting leader is: johannh

General Topics / Roundtable

  • Next meeting is during All Hands. Cancel?
    • Yes

Friends of the Firefox team


Resolved bugs (excluding employees)

Fixed more than one bug

  • Itiel
  • Logan Smyth [:loganfsmyth]
  • Michael Hoffmann
  • Oriol Brufau [:Oriol]
  • Tim Nguyen :ntim

New contributors (🌟 = first patch)

  • <Will be filled out after the meeting>

Project Updates


  • No updates

Add-ons / Web Extensions

  • WebExtensions Framework:

    • Shane introduced a new ExtensionPreferencesManager method to retrieve the list of the preferences controlled by extensions (Bug 1595860). This new method is meant to be used in follow ups for about:support, Bug 1461447, and about:config, Bug 1595865).

    • Some new in-tree docs related to the ExtensionSettingsStore and the ExtensionPreferencesManager internals has been recently landed (Bug 1599918):

    • As part of the Fission-related changes on the WebExtensions framework, Tomislav has added an explicit check to verify that the sender of the IPC messages exchanged internally are not being spoofed (Bug 1604058)

  • WebExtensions APIs

    • The `inspect(...)` method (available to the extension’s JS code executed using the `browser.devtools.inspectedWindow.eval` API method) is now able to select a function object passed to it in the DebuggerPanel (Bug 1605597)

      • this feature is used by the React DevTools extensions and it is going to allow the React DevTools extension to re-enable this feature when running on Firefox \o/
  • Addon Manager and about:addons:

    • The “Recommendations” message bar (part of the about:addons Recommendations view) can now be dismissed by a user (Bug 1564518). Thanks to Trishul for contributing this change!


Firefox Accounts

Sync and Storage


Browser Architecture

  • Gjs and mconley are mentoring some MSU students working on porting more strings to Fluent

Developer Tools


  • Alex Surkov implemented autoscroll
  • Neil implemented WebRTC
  • There are plans for a Introduction to Fission Engineering presentation at the Berlin all hands. Stay tuned for more details.
  • Alex wrote some notes he made while getting started with fission development that might be of interest.


New Tab Page

  • Doing some Q1 planning. Pocket side of newtab is moving to more of a user experience/user story first focus.
  • Keeping moving on some personalization improvements for future features. (behind a pref)
  • Looking at starting to enable content in other locales.


  • Stuff is moving along slowly, more to announce soon

Password Manager


  • This quarter, the team is focused on:

    • Shutdown performance

    • Egregious startup times

  • dthayer is adding a new pref for experimenting with faster shutdown techniques
  • emalysz improved our ability to insert or modify large sets of tabs at once, which is great for large sessions being restored!
  • emalysz also has a patch up for unifying how we cache XUL fragments for our custom elements
  • Gijs improved the performance of the addon blocklist for entries that have long regular expressions in them
  • mconley found a bug in how we measure the time to about:home first paint in some cases, which might account for some of the egregious start times we’re recording
  • mconley is finishing up an about:home performance audit, aiming to have it done in time to present to the about:home team by Berlin

Performance Tools

  • No updates this week.


  • Picture-in-Picture shipped enabled by default in Firefox 72 on macOS and Linux! \o/
  • We’re aware of a bug on certain flavours of Linux where the player window starts to shrink down after opening. Martin Stransky from Red Hat is on the case, and has a patch.
  • We landed a patch that lets us use the WebCompat add-on to reposition the toggle for specific sites. We haven’t tried deploying any of these repositions yet, but stay tuned.


Remote Debugging (Chromium Protocol) (read-only)

Search and Navigation


Address Bar:

User Journey

  • Successful test experiment using FirstStartup to change behavior on first run
  • Running a personalization experiment using machine learning to optimize when to show CFR
  • AttributionCode now accepts “ua” for bedrock + stubatribution service to pass along the user agent for telemetry and messaging targeting

This week I learned

  • [mconley] Are you using JSWindowActors? Are you cleaning up when the actor goes away? Use `didDestroy` and not `willDestroy`.
  • [harald] `toLocaleTimeString` can allocate massive amounts of memory if used in hot code – reuse the same `DateTimeFormat` instance (bug 1603276)
  • [Gijs] followlines in blame on hgweb to see when a range of lines what changed