Bug 287901 – Add ITP debugging features to advance time of active use impacting WebKit Storage

• Status: NEW
• Component: Page Loading

[Niall Kennedy]

A developer would like to test how ITP functionality of the Safari browser on iOS impacts their sites. They enabled Web Inspector in Safari advanced settings and the "ITP Debug Mode" is enabled.

The developer identifies the type of penalty applied based on the ITP debug log. `[ITP] Applying cross-site tracking restrictions to: [mydomain.org]`

They'd like to step forward in time, applying any future penalty and/or removing the restriction after N days of use have passed. An operating date would advance with each ITP debug instruction to increment time. New ITP records may display as a result: `[ITP] Done removing data records`.

A developer should be able to inspect the new state of their site storage after they've advanced ITP beyond the operating window of the penalty.

[Niall Kennedy]

Alternatives considered (but dismissed as not fully addressing:

# Manually remove a domain as tracking capable

`ResourceLoadStatisticsManualPrevalentResource` can manually set a domain as tracking capable in environments that allow writing User Defaults for Safari. There's no equivalent for removing a value from a prevalent resource list.

The impact of the applied penalty (or penalties) might be unclear to the developer in this situation. A storage deletion action could include:
* all cookies
* all but HTTP only cookies
* all script written cookies

Incrementing days beyond an operating window, and tapping into related storage cleanup, should be more straightforward for a developer than adjusting a request to read the same storage.

# Trigger a specific time window

The developer likely wants to advance beyond a specific operating dates window, such as 7 days or 30 days. These days of active use variables could change their assigned values, or new variables could be introduced, requiring a developer to remap expectations.

Movement within an existing expected increment of WebKit Storage may be preferred.

# Advancing system time

A developer could set their system time to 24 hours in the future and load a webpage in Safari that would have no new impact on their domain's ITP classification. They would have no confirmation from Safari if a day of active use was recorded.

A developer would like to confirm their intended action was applied by Safari. Setting a device time into the future, if allowed by the device, would not confirm developer intent.

[Radar WebKit Bug Importer]

<rdar://problem/145607023>