opening lots of tabs via "ctrl+t" and quickly closing them using "ctrl+w" created dead tabs

[kjozwiak]

Test plan

#11311 (comment)

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- Did you search for similar issues before submitting this one?

Yes

- Describe the issue you encountered:

When opening large quantities of tabs using "ctrl+t" and than quickly closing them using "ctrl+w", you'll sometimes get "dead" tabs that cannot be closed or used. If you manage to create a lot of these dead tabs, "ctrl+w" eventually stops working.

The UI is still responsive and the user can always restart so it's not as bad as #9083.

- Platform (Win7, 8, 10? macOS? Linux distro?):

macOS 10.12.16 x64 - Reproduced
Win 10 x64 - Reproduced

- Brave Version (revision SHA):

Brave 0.18.33

- Steps to reproduce:

1. Open Brave and start creating a lot of tabs via "ctrl+t"
2. Once you have a page or two worth of tabs, quickly switch over and start pressing "ctrl+w"

- Actual result:

Some of the tabs will become "dead" and cannot be closed or used. Going through the above STR, you'll sometimes manage to create ~10 dead tabs. When this happens, "ctrl+w" stops working.

- Expected result:

Tabs should be easily created and closed without creating dead tabs. When this happens, "ctrl+w" shouldn't break and should always work as expected.

- Will the steps above reproduce in a fresh profile? If not what other info can be added?

Yes

- Is this an issue in the currently released version?

Yes

- Can this issue be consistently reproduced?

Yes

- Screenshot if needed:

[bbondy]

0.19.x: 511bf20
0.20.x: 7bb5286
master: bf4726d

[srirambv]

No dead tabs but causes crash(#11322)

[srirambv]

Found one dead tab when opened a lot of tabs(5 tab pages) holding Ctrl+T and closing tabs(4 tab pages) by holding down Ctrl+W.

[srirambv]

Same single dead tab on 0.20.8 as well