*Contact emails* johni...@chromium.org, wanderv...@chromium.org, lin...@chromium.org
*Explainer* https://github.com/privacysandbox/tpcd-labeling/blob/main/cookie_deprecation_labeling_explainer.md https://developer.chrome.com/en/docs/privacy-sandbox/chrome-testing *Specification* None *Summary* To prepare for the third-party cookie deprecation, it is important to understand the full impact of Chrome’s planned transition from third-party cookies to the Privacy Sandbox Ads APIs. This experiment exposes a temporary set of APIs which provide access to browser-determined treatment and control groups to support opt-in server side testing of the third-party cookie deprecation. *Blink component* A-N/A *TAG review* Not requesting TAG review as this API is a temporary Chrome-specific experiment. *Risks* *Interoperability and Compatibility* This feature is only shipping in Chrome to support the third-party cookie deprecation, and will not be interoperable with other vendors. *WebView application risks* Not available on WebView *Goals for experimentation* The goal of this experiment is to allow adtechs to evaluate the impact of third party cookie phase out through opt-in server side testing. We expect partners to run experiments downstream from the browser provided treatment and control groups. *Experiment Behavior and Risks* This experiment will expose temporary APIs which allow access to browser provided experiment labels. To ensure all parties can easily get access to labels, we intend to expose the APIs without a traditional origin trial. To limit burn-in risk, the new APIs will only be available to at most ~10% of users. These APIs should have very little utility to developers outside of this specific temporary experiment, it seems unlikely that user-visible breakage would occur as a result of the eventual removal. *Timeline* We intend to remove the labeling APIs when Mode B of the experiment ends, which we expect to be by the end of Q2 2024 at the earliest. This experiment temporarily adds a new surface to the web that could be used for active fingerprinting. This is mitigated by the fact that: - only a subset are assigned labels, reducing the usefulness of the label for fingerprinting - labels are not sent for users who block third-party cookies, to ensure consistency with those users’ current settings - the labeling APIs will be removed by the time third-party cookies are phased out - label assignment is independent of users' browsing activity *Ongoing technical constraints* None *Debuggability* None *Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?* No, not supported on WebView. *Is this feature fully tested by web-platform-tests?* No *Flag name on chrome://flags* #tpc-phase-out-facilitated-testing *Requires code in //chrome?* False *Estimated milestones* Experiment desktop first 119 Experiment Android first 119 *Intent to Prototype* https://groups.google.com/a/chromium.org/g/blink-dev/c/8mlWTOcEzcA/m/NZJSW0weAQAJ *Link to entry on the Chrome Platform Status* https://chromestatus.com/feature/5189079788683264 -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/232aa6ed-bb1e-4954-b290-f178b7edd7c1n%40chromium.org.
