I don't think undoing a "clear" action after it has started is possible. Adding a confirmation dialog seems much simpler.

@dullweber do you know who would be the right person to flesh out when should such a dialog be shown in CBD (always, if more than a certain amount of entries are cleared?)

Undoing a deletion is currently not possible. Is it an accessibility requirement/best practise to have a way to undo destructive actions because it is easier to trigger the deletion by accident when using a screenreader? 

Currently the default behavior for CBD is that history, cookies and cache are deleted for the last hour. This is not very destructive, so users would have to select more sensitive options like deletion of passwords or all history before something valuable would be lost.

I could imagine that we might want to protect some very valuable data (like auto-generated passwords) but in general I don't think that a confirmation is neccessary.

+maxwalker@ for UX discussions

We could show a confirmation dialog *only* when a screenreader is present. Presumably we can detect that?

Even if it were possible to detect that a screenreader is in use reliably, I'm not sure that's a good approach.

When the dialog opens, pressing enter clears the last hour of browsing history, cookies and cache. The basic tab is initially open with three checkboxes and all of them are checked. We could have none checked as a default. The default action is then disabled (pressing enter does nothing).

Download history is selected by default in the advanced tab of the dialog. In basic, download history is not cleared.

For the advanced tab passwords, autofill data, content settings, hosted app data and media licenses are not selected.

Currently we have implemented undo for download history and bookmark. Bookmarks are not modified by the CBD dialog. For downloads, only the downloaded items removed while the downloads tab is open can be undone with a ctrl+z shortcut. If the downloads history tab is reloaded, the removed items cannot be brought back with undo.

I'm not sure undo is what we want here. It's not clear what undo should in certain cases like site data, media licenses and cache. I think having either appropriate defaults or a cautionary confirmation.

My preference would be for the dialog to open each time with no checkboxes selected and the time interval set to the last hour.

Accidentally deleting cookies, cache or history for the last hour doesn't really break much, so I don't think that it is necessary to unselect everything.
Many users regularly delete data for all time. Resetting the time interval would be quite annoying to them. The same holds for resetting the checkbox selection.

Is there a higher risk to do an accidental deletion with a screenreader than otherwise?

We could consider resetting some selections (e.g. always start on the basic tab, where the dangerous stuff like password deletion is not available) but I don't think resetting too much state or resetting it for all users would be a good idea.

My preferred approach would be a confirmation dialog that is only shown if specific conditions hold. E.g. if you would delete multiple passwords or a lot of history.

A confirmation dialog that only shows when a particularly destructive clearing may occur (greater than 24 hours or when passwords or media licenses are checked) sounds good to me.

Here is a potential confirmation dialog for CBD. Should the dialog show up all the time?

Deleted: Screenshot from 2019-01-14 14-32-54.png 74.0 KB

	Screenshot from 2019-01-14 14-32-54.png 74.0 KB View Download

I think that it is best to talk with UX about this. I will ask Max and we soon have a new person for privacy UX, who might work on this.

We might want to mention the important pieces of data that will get deleted. E.g. "This will delete 25 passwords" - cancel/confirm.