[Feature] Disable "ImprovedCookieControls" feature in Chromium by default

[alexduhanov]

Chromium 84.0.4131.0 includes the flag "Enable improved cookie controls UI in incognito mode" turned on by default, which will block third party cookies in Incognito mode.

Given that Playwright runs its tests in Incognito mode by default, this may be disruptive to users.

I was able to get around the issue by setting this flag to the browser launch options:

args: [
    '--disable-features=ImprovedCookieControls',
],

But it may be of benefit to others to have Playwright launch Chromium with this option disabled by default.

Note: this only seems to affect headful runs.

[pavelfeldman]

@alexduhanov do you have a repro this this one? I have a test that passes on Chromium and allows third party cookies both in persistent and non-persistent contexts...

[alexduhanov]

@pavelfeldman is your test running in headful mode? the issue doesn't seem to affect headless chromium

[alexduhanov]

@pavelfeldman - I don't have a repro for this one as I'm hitting a proprietary login server in my actual test, but I can confirm that the flag allows my test to pass.

How were you able to test the third party cookies? Since the cookie must exist on a different domain, I'm not sure how to do this myself without a remote service that my test can talk to, or through some hosts file manipulation.

[aslushnikov]

How were you able to test the third party cookies?

@alexduhanov You can use http://localhost and http://127.0.0.1 as two different origins (this is what is done in https://github.com/microsoft/playwright/pull/2073/files).

[pavelfeldman]

I think these are all aligned and tested now. Please feel free to reopen.

[alexduhanov]

I haven't had any issues, thanks so much!