Sync UI thread hangs

[AlexeyBarabash]

Description

A quite rare situation which I could see during work on brave/sync#290 on 0.64.x master . After re-basing master to 0.65.x I could not see the issue .

Because I had not figured the reason, created the issue.

Steps to Reproduce

1. Adjust computer time 15 minutes forward
2. Get empty profile
3. Run Brave browser
4. brave://sync, Start a new Sync Chain
5. Cancel
6. Close browser
7. Repeat pt3 for several times

Actual result:

Sometimes UI hangs, and does not response on mouse and keyboards.

Expected result:

No hung.

Reproduces how often:

Intermittent issue

Brave version (brave://version info)

Saw it on master 0.64.x, and could not repsoduce after migration to 0.65.x

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds?

Website problems only:

• Does the issue resolve itself when disabling Brave Shields?
• Is the issue reproducible on the latest version of Chrome?

Additional Information

[JoelMon]

Can reproduce on Linux Mint using Version 0.64.30 Chromium: 73.0.3683.75 (Official Build) dev (64-bit).

When I try to remove a device from the sync chain it hangs. I recorded the problem. Can be seen here.

[AlexeyBarabash]

@JoelMon for the situation you had recorded, removing of the device can take up to 1 minute until sync will get confirmation from the server about removing of the device.

[AlexeyBarabash]

The original issue is not related to sync and was fixed on my Ubuntu 16 computer by disabling Nvidia proprietary drivers.