1712038 - YouTube Video Automatically Exits Full-Screen Mode When Another YouTube Tab Opened in Background Finish Loading With Fission Enabled

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect, P2)

Description

[SL]

Steps to Reproduce

1. Ensure you have Fission enabled.
2. Open any YouTube video and enter full-screen mode.
3. While in full-screen mode, scroll down to the suggested videos section and open any one of them in a new tab.
4. Wait and observe.

Expected Result

Nothing visible happens while the newly opened video in another tab loads in the background.

Actual Result

When the newly opened video in another tab finishes loading, the currently-focused video automatically exits full-screen mode, for some reason.

Additional Information

• This bug does not reproduce when Fission is disabled (setting fission.autostart to false and restarting the browser).
• Unfortunately, I was unable to obtain the regression range for this bug since even the earliest build available contains this bug.

Comment 1

[Chris Peterson [:cpeterson]]

Thanks for the bug report, SL! I can reproduce this Fission bug on my Windows 10 laptop.

I tested opening the second video in a new tab using Ctrl+click and with right-click > "Open Link in New Tab". I could reproduce with either method.

Comment 2

[Edgar Chen [:edgar]]

I could also reproduce this, taking the bug.

Comment 3

[Edgar Chen [:edgar]]

The exit of fullscreen is due to the focus changes, https://searchfox.org/mozilla-central/rev/08f063f4c89d270fd809fc0325b5a9000ae87d63/dom/base/nsFocusManager.cpp#1625, and it is from

0 focusOnPlayer/<() ["https://www.youtube.com/s/desktop/3ce082d6/jsbin/desktop_polymer.vflset/desktop_polymer.js":15436:223]
this = [object HTMLElement]
1 pra(a = "undefined") ["https://www.youtube.com/s/desktop/3ce082d6/jsbin/desktop_polymer.vflset/desktop_polymer.js":3502:47]
2 ora/</<() ["https://www.youtube.com/s/desktop/3ce082d6/jsbin/desktop_polymer.vflset/desktop_polymer.js":3500:157]
this = [object Window]

Comment 4

[Edgar Chen [:edgar]]

Attachment: test.html

Here is the test script to reproduce the similar behavior.

1. Enter the button to enter fullscreen
2. ctrl+click the link to open a background tab.

Comment 5

[Edgar Chen [:edgar]]

Comparing the behavior with STR in comment #0 on Fission and non-Fission, non-Fission don't encounter the issue is just because the background tab wouldn't try to focus the player element, not sure why, but anyhow, the focus() call on background tab should not cause the fullscreen get exited.

So this actually isn't a Fission specific issue, we could also reproduce this on non-Fission with the test attached in comment 4.

I ran mozregression and got following range,
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=46e1717494fbf0f1913e22052c3304fe9f7c19b8&tochange=3f72a81bd12cb6048f03a96e5b403621f7fac052

Probably caused by bug 1432856.

Comment 6

[Edgar Chen [:edgar]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=b0988da9c764a47b091806e8aef6e2604a87d73c

Comment 7

[Olli Pettay [:smaug][[e-mail]]]

But if the real world example is Fission only, I think this should be tracked as part of Fission.

Comment 8

[Edgar Chen [:edgar]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=5820fdb6e7b97134c2fa12507865d0b499f255bd

Comment 9

[Edgar Chen [:edgar]]

Attachment: Bug 1712038 - Exit fullscreen only when the focus change will raise the window; r=smaug

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a9fa2b1591c7
Exit fullscreen only when the focus change will raise the window; r=smaug

Comment 11

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/a9fa2b1591c7