Show where a domain was seen tracking

[ghostwords]

Let's expose snitch map in the popup UI, to make debugging user issues (examples: one, two) easier.

Suggested UI: Hidden by default, revealed by hovering over domain entries in the popup. Currently hovering reveals a tooltip. Let's add some version of "why was this blocked?" (just "why" next to blocked? probably need to redesign the tooltip), clicking which should reveal the snitch map entries.

To start addressing privacy concerns (#266 (comment)), let's at least be sure to clear already-used (>TRACKING_THRESHOLD) snitch map entries upon history clearing events.

This is phase one of implementing #963.

[ghostwords]

Note that currently snitch map never gets cleaned up.

[ghostwords]

Let's ask for this info in the CONTRIBUTING doc, under how to report broken sites.

[jawz101]

I like this idea. It'd be nice to see the prevalence of a tracker. It'd also tie into my opt-in idea.

The EFF could write articles on that sort of data.

[ghostwords]

I don't see a way to be notified of history-clearing events at this time without asking for the "history" permission, which will trigger a new permission warning, which seems unacceptable for Privacy Badger at this point (will lose a significant percentage of users in Chrome, and have a similar percentage stop upgrading in Firefox).

[jawz101]

Given my past experiences in IT support, people freak out when anything changes and then get over it. It's clearly not intended to compromise privacy. If anything, I might explain it in a blog post with an explanation and a bar napkin drawing visualizing how it would operate and remain local.

My only thought is that it would need to be a cool enough visualization to be worth seeing. Personally, I would think a visualization of how the program has learned what to block over time would be more interesting. Either way, a dashboard of charts and stuff or something would be cool.

[ghostwords]

@bcyphers Picking up from #2130:

Good point about effort; if we can do something quick and simple, let's do it.

As your mock suggests, we don't have to do this in both the popup and the options page; we can do this in the options page alone, which gives us more flexibility.

We shouldn't use the words "snitch map" in user-facing things I think, as it seems to be needless jargon. This can say something like "example.com was seen tracking on:" instead.

We should probably show output for the base domain and all of its children, similar to how our manual debugging code works.