1690368 - updateFxaToolbarMenu touches the DOM between 2 style flushes

Status: RESOLVED FIXED

(Firefox :: Firefox Accounts, defect)

Description

[Florian Quèze [:florian]]

See this profile of opening a new window: https://share.firefox.dev/2MOfObn

Focusing the url bar triggers a sync style flush (see bug 1445811 for what we could do about it), then updateFxaToolbarMenu makes the DOM dirty by calling Element.setAttribute and then we flush styles again during the refresh driver tick.

Without knowing anything about what the FxA code is trying to do, it feels like swapping these 2 lines would save us a style flush: https://searchfox.org/mozilla-central/rev/b2433a832c250c55255e0ee37d05192d04f20427/browser/base/content/browser.js#1768,1770

Looking at the code actually setting an attribute (https://searchfox.org/mozilla-central/rev/b2433a832c250c55255e0ee37d05192d04f20427/browser/base/content/browser.js#699) I wonder if this attribute really needs to be set dynamically or if it could be in the initial markup of browser.xhtml.

Comment 1

[Florian Quèze [:florian]]

Attachment: Bug 1690368 - call updateFxaToolbarMenu before focusing the urlbar causes a style flush, r=markh.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/280bdc634f73
call updateFxaToolbarMenu before focusing the urlbar causes a style flush, r=markh.

Comment 3

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/280bdc634f73