Add settings section for clearing browser history

[JayKid]

Description

Minimal version of the settings pane to clear browsing history.

Sadly, the functionality is not there:

1. First attempt was to use places.deleteAllHistory() but it's not available in this scope and I can't use require/import to fetch it

2. Tried using directly postMessage as places internally does but that postMessage within places is directed to the particular worker so this didn't work either

Also, I used inline styles which should be migrated to some stylesheet, but just wanted to put a quick PoC together to ask for pointers when it comes to actually clearing the DB of its stored URLs.

New settings section

[PalmerAL]

The right way to do this would be postMessage to the preload script -> send an IPC from there (like this) -> have an IPC listener in the UI process that calls places.deleteHistory(). But I'm not sure that's really the right solution anyway - there's a "clear all history" button in the history view already. So I think what we want is just the "clear history on closing the browser" part.

For that, you'd need two things:

1. History gets written to disk here: https://github.com/minbrowser/min/blob/master/js/places/placesWorker.js#L165. If the setting is enabled you'd want to skip that and just keep it in-memory.
2. When the app is quit, you'd need to clear cookies and site data. The Electron API for this is asynchronous, so you'd need to restructure the quitting process a bit to let that finish before quitting.

But thinking about this more (and I'm thinking and writing this at the same time), I wonder if "clear history on quit" is really the right behavior:

• Some people leave their browser open for weeks and never quit, and so this isn't useful to them.
• If you accidentally quit in the middle of a session and re-open, all your history is gone.
• Some people might want to keep history for a shorter time (like 1 week), which this doesn't do anything for.

So another, possibly better, way we could do this would be:

• Have some different options for how long to keep history, from 1 hour up to the current time of 6 weeks.
  • That would affect this value.
• Whenever we delete an item from history, check whether there are other items from that domain still in history. If there are none left, call clearStorageData for that domain.
  • I think this would also provide a privacy improvement for users who keep the default setting of 6 weeks, since cookies can sometimes last longer than that.