Cookie exception to unbreak Google logins

[mrzealot]

Fixes brave/brave-browser#3534.

This PR wires in the already existing cookie exception checking method to the cookie blocking workflow, adds capability for 1st-party-independent exceptions (e.g., specific iframe hosts that should be allowed to access cookies no matter the hosting site), and adds an exception to https://accounts.google.com/o/oauth2/* to allow iframe-based Google login integration on many sites, as per our slack discussions.

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Windows
  • macOS
  • Linux
• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests) on
  • Windows
  • macOS
  • Linux
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone

Test Plan:

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

[diracdeltas]

Please link in the PR to the issue this is fixing (creating an issue if one doesn't exist already) and squash commits into one commit

[fmarier]

I would suggest adding two test cases in common/shield_exceptions_unittest.cc:

• A positive test case:

  EXPECT_TRUE(IsWhitelistedCookieException(GURL("https://www.airbnb.com/"),
                                           GURL("<actual Google URL used AirBnB uses minus query string>")));
  

• A negative test case:

  EXPECT_FALSE(IsWhitelistedCookieException(GURL("https://www.mozilla.org/"),
                                            GURL("https://www.googletagmanager.com/gtm.js")));
  

[fmarier]

The commit message (and this PR as @diracdeltas pointed out) is missing a link to the issue that it is fixing.

Other than that, it looks good to me.

[mrzealot]

Oh sorry, I wasn't familiar with the formatting expectations and thought the above reference to brave/brave-browser#3115 was enough. Made a more generic issue to link this to, referenced it in the description, and also re-pushed the changes with a more appropriate message.

[fmarier]

In the commit messages, the syntax also requires brave/brave-browser#1234 since these issues are not in the brave/brave-core repo.

[bbondy]

This was added here ec009bb as part of an option that can be disabled. Closing this PR.