Bug 264852 – Make Clear-Site-Data HTTP header work as expected in ephemeral sessions

• Status: NEW
• Component: WebCore Misc.

[sideshowbarker]

In an ephemeral session, the current implementation doesn’t handle the Clear-Site-Data HTTP header fully as expected — as evidenced by the WebKit test results at https://wpt.fyi/results/clear-site-data/storage.https.html, which show two failures and a timeout.

Browsing in Safari to https://wpt.live/clear-site-data/storage.https.html in a normal (non-private) window shows that all those tests are actually fully passing/green.

But browsing to that same URL in a private window shows the same test failures as what https://wpt.fyi/results/clear-site-data/storage.https.htm shows.

The wpt.fyi infrastructure runs SafariDriver, which creates ephemeral sessions for test runs. So the results overall (from wpt.fyi and from manually opening the wpt.live test page in private window) seem to indicate that the implementation for handling the Clear-Site-Data HTTP header doesn’t work full as expected in ephemeral sessions.

[Radar WebKit Bug Importer]

<rdar://problem/118700909>

[sideshowbarker]

With https://commits.webkit.org/273763@main now landed, the relevant test-case failure can be reproduced on a local trunk build by calling “run-webkit-test” like this:

run-webkit-tests --additional-header='useEphemeralSession=true' \
  imported/w3c/web-platform-tests/clear-site-data/storage.https.html