1373378 - Make layout/reftests/async-scrolling/position-fixed-iframe-2.html pass on linux64-qr with APZ enabled

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P3)

Description

[Kartikaya Gupta (email:[e-mail])]

With WR+APZ enabled, the layout/reftests/async-scrolling/position-fixed-iframe-2.html reftest fails. This bug is for the patches that make it pass, without regressing any "earlier" tests.

Comment 1

[Kartikaya Gupta (email:[e-mail])]

Problem here seems to be that the fixed-pos div inside the iframe gets fixed to the root scrollframe of the root content document, instead of the iframe's root scrollframe.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

The reason this happens is that the scrolling container that the fixed item is fixed to is no longer on the stack when we encounter the fixed item. It has already been popped off by that point. We can improve wr::DisplayListBuilder::ParentScrollIdFor to fix this.

Comment 3

[Kartikaya Gupta (email:[e-mail])]

Try pushes with and without APZ:

https://treeherder.mozilla.org/#/jobs?repo=try&revision=b0f44742dfd5e91b9dbe3ca16bb2c4f4bbbbded3
https://treeherder.mozilla.org/#/jobs?repo=try&revision=10b0c91a74675f305391eb886df9c7decf27ed6f

Comment 4

[Kartikaya Gupta (email:[e-mail])]

Attachment: Bug 1373378 - Do a better job tracking the ancestor scrollids in DisplayListBuilder.

In some cases we need to know the ancestor scrollid of a scrollid that we had
previously pushed onto the stack and then subsequently popped off. Since that
scrollid is no longer actually on the stack at the time of the query, we would
return Nothing(). Instead, this patch adds a map to "remember" previously
encountered scrollids and their ancestors, so that these queries can be correctly
handled.

Review commit: https://reviewboard.mozilla.org/r/149936/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/149936/

Comment 5

[Jeff Muizelaar [:jrmuizel]]

Comment on attachment 8878641 [details]
Bug 1373378 - Do a better job tracking the ancestor scrollids in DisplayListBuilder.

https://reviewboard.mozilla.org/r/149936/#review155268

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0dbc79e5d74d
Do a better job tracking the ancestor scrollids in DisplayListBuilder. r=jrmuizel

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/0dbc79e5d74d