Disable FLoC

[kdzwinel]

Reviewer: @jonathanKingston
Tech Design: https://app.asana.com/0/481882893211075/1200159597529958/f

Description:

This disables FLoC API by opting all sites out of FLoC and removing the JS API.

Steps to test this PR:

1. run chrome (89+) with flags that force FLoC on:

/Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --enable-blink-features=InterestCohortAPI --enable-features="FederatedLearningOfCohorts:update_interval/10s/minimum_history_domain_size_required/2,FlocIdSortingLshBasedComputation,InterestCohortFeaturePolicy"

1. clear browsing history

2. visit couple of websites

3. verify that document.interestCohort() doesn't return a cohort number (in context where we don't block the API - e.g. safelisted or any chrome:// page)

4. verify that document.interestCohort() is not available (in context where we block the API)

Make sure that:

• this works on sites that alrady have permissions-policy header (e.g. https://scotthelme.co.uk/goodbye-feature-policy-and-hello-permissions-policy/ , https://securityheaders.com/)
• permissions-policy opt-out header should be on all frames (main and sub)
• safelisting the site should bring back the JS API but the opt out header should still be there
• verify that it's not causing issues when running in Chrome with FLoC not force-enabled

Automated tests:

• Unit tests
• Integration tests

Reviewer Checklist:

• Ensure the PR solves the problem
• Review every line of code
• Ensure the PR does no harm by testing the changes thoroughly
• Get help if you're uncomfortable with any of the above!
• Determine if there are any quick wins that improve the implementation

PR Author Checklist:

• Get advice or leverage existing code
• Agree on technical approach with reviewer (if the changes are nuanced)
• Ensure that there is a testing strategy (and documented non-automated tests)
• Ensure there is a documented monitoring strategy (if necessary)
• Consider systems implications

[jonathanKingston]

LGTM now! Thanks

[dharb]

Looking good! Just one tiny fix, then we should be ready to ship.

[dharb]

👍 💥