Bug 213110 – REGRESSION (r262124): Twitter videos go blank after exiting fullscreen

• Status: RESOLVED
• Resolution: FIXED
• Component: Layout and Rendering

[Simon Fraser (smfr)]

Summary:
Twitter videos go blank after exiting fullscreen

Steps To Reproduce:
1. Load https://twitter.com/stephentyrone/status/1271230268762992642 in Safari
2. Take the video fullscreen
3. Exit fullscreen

Results:
The area where the video should be is blank.

Regression:
I regressed this to https://trac.webkit.org/changeset/262124/webkit

[Sergio Villar Senin]

We'll check. It's weird because I cannot reproduce it with WebKitGTK

[Peng Liu]

Is FULLSCREEN_API enabled for WebKitGTK? Looks like it is not. Then this issue affects Mac version only.

[Peng Liu]

<rdar://problem/64282632>

[Simon Fraser (smfr)]

Can we revert the change for now?

[Sergio Villar Senin]

(In reply to Simon Fraser (smfr) from comment #4)
> Can we revert the change for now?

Reverted for now while investigating.

[Sergio Villar Senin]

(In reply to Peng Liu from comment #2)
> Is FULLSCREEN_API enabled for WebKitGTK? Looks like it is not. Then this
> issue affects Mac version only.

Not by default, but it's implemented. After building with it enabled I cannot reproduce the test case in WebKitGtk either. I'm wondering whether there is some special code in twitter depending on the UA that could cause the issue. Still checking

[Sergio Villar Senin]

(In reply to Sergio Villar Senin from comment #6)
> (In reply to Peng Liu from comment #2)
> > Is FULLSCREEN_API enabled for WebKitGTK? Looks like it is not. Then this
> > issue affects Mac version only.
> 
> Not by default, but it's implemented. After building with it enabled I
> cannot reproduce the test case in WebKitGtk either. I'm wondering whether
> there is some special code in twitter depending on the UA that could cause
> the issue. Still checking

BTW the issue if any will be with the interaction between RenderFlexibleBox and RenderFullscreen (derived) more than with the FULLSCREEN_API which is different stuff.

[Sergio Villar Senin]

(In reply to Sergio Villar Senin from comment #7)
> (In reply to Sergio Villar Senin from comment #6)
> > (In reply to Peng Liu from comment #2)
> > > Is FULLSCREEN_API enabled for WebKitGTK? Looks like it is not. Then this
> > > issue affects Mac version only.
> > 
> > Not by default, but it's implemented. After building with it enabled I
> > cannot reproduce the test case in WebKitGtk either. I'm wondering whether
> > there is some special code in twitter depending on the UA that could cause
> > the issue. Still checking
> 
> BTW the issue if any will be with the interaction between RenderFlexibleBox
> and RenderFullscreen (derived) more than with the FULLSCREEN_API which is
> different stuff.

Good news is that I managed to repro it using WebKitGtk so it'll be much easier to get a fix.

[Simon Fraser (smfr)]

Was reverted in https://trac.webkit.org/changeset/263018/webkit

[Sergio Villar Senin]

Created attachment 402230 [details]
Patch

[Sergio Villar Senin]

Created attachment 402464 [details]
Patch

Test working now in Mac/iOS

[Sergio Villar Senin]

Committed r263389: <https://trac.webkit.org/changeset/263389>

[Karl Rackler]

Created https://bugs.webkit.org/show_bug.cgi?id=213517 for the test because it is flaky failing since introduction.