1400393 - Chrome flashes sometimes when hovering tabs

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P1)

Description

[Jeff Muizelaar [:jrmuizel]]

I'm not sure what causes it, but it looks like the images are going away. Maybe nicals stuff will help.

Comment 1

[Aria Beingessner [:Gankra]]

When I was testing with nicals stuff to see if the crasher was gone, it didn't seem to help.

Comment 2

[Vincent Liu[:vliu]]

(In reply to Alexis Beingessner [:Gankro] from comment #1)
> When I was testing with nicals stuff to see if the crasher was gone, it
> didn't seem to help.

Can you please have a more information about nical stuff to test? I've never hear about it and I want to also reproduce it with this nical stuff on my local machine. Thanks

Comment 3

[Aria Beingessner [:Gankra]]

We're talking about these two patches:

https://bugzilla.mozilla.org/show_bug.cgi?id=1393031

https://bugzilla.mozilla.org/show_bug.cgi?id=1397407

Comment 4

[Markus Stange [:mstange]]

This is a webrender bug: https://github.com/servo/webrender/issues/1893

When you hover the tabs, there's an off-main-thread animation for the tab line which starts at scaleX(0). That singular matrix seems to break things in webrender.

My usual method of getting a YAML representation of the broken frame did not work. This was because "wrench --save yaml replay" does not reflect values that are changed through property bindings. The frames were generated like this:
 - set display list with stacking context and good transform
 - generate frame [frame 1, renders correctly]
 - generate frame with the property binding updated to the bad transform [frame 2, is broken]
 - set display list with empty stacking context and bad transform
 - generate frame [frame 3, renders correctly again]

I think the first two generate frame calls cause the creation of two separate YAML files, but the second file has the same contents as the first and the matrix value is not updated.

For a while I was looking at frame 3, because it has the bad transform in it, but it renders correctly because the stacking context is completely empty, because Gecko identified the singular transform and culled the contents.

Comment 6

[Markus Stange [:mstange]]

Tweaking summary because this happens on Linux as well.

The upstream webrender bug is fixed, and the fix will be picked up in the next webrender update (bug 1409736).

Comment 7

[Markus Stange [:mstange]]

Fixed by the webrender update.