878801 - BrowserNewTabPreloader needs to query tabbrowser bounds without flushing pending layout changes

Status: RESOLVED FIXED

(Firefox :: Tabbed Browser, defect)

Description

[Tim Taubert [:ttaubert] (inactive)]

Silly me introduced another uninterruptible reflow while fixing bug 875257. The BrowserNewTabPreloader must not query window.gBrowser.boxObject when opening new tabs or else this will again cause us to flush pending layout changes.

Comment 1

[Tim Taubert [:ttaubert] (inactive)]

Attachment: part 1 - introduce nsIDOMWindowUtils.getBoundsWithoutFlushing()

This patch adds .getBoundsWithoutFlushing() to nsIDOMWindowUtils which is the equivalent to DOMElement.getBoundingClientRect() without flushing pending layout changes.

Comment 2

[Tim Taubert [:ttaubert] (inactive)]

Attachment: part 2 - query tabbrowser bounds without flushing layout

Comment 3

[Tim Taubert [:ttaubert] (inactive)]

I forgot to note that it's totally ok for the BrowserNewTabPreloader to work with bounds that are possibly not up-to-date as we're optimizing for the average case where a user does not resize their window every time before opening a new tab (even if so there's a good chance something else will flush the layout for us). The code does still work with "incorrect" bounds.

Comment 4

[Jared Wein [:jaws] (please needinfo? me)]

Comment on attachment 757405 [details] [diff] [review]
part 2 - query tabbrowser bounds without flushing layout

Review of attachment 757405 [details] [diff] [review]:
-----------------------------------------------------------------

rs=me

Comment 5

[Tim Taubert [:ttaubert] (inactive)]

https://hg.mozilla.org/integration/fx-team/rev/40216a220b80
https://hg.mozilla.org/integration/fx-team/rev/ce5ab0de1b09

Comment 6

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/40216a220b80
https://hg.mozilla.org/mozilla-central/rev/ce5ab0de1b09