Allow clearing the extension storage #2669

I've long thought of a "service" dropdown in the options for this and options export, but we could just list them after the features list.

The first item this should be super easy to implement:

<h2>Debugging</h2>
(... Checkbox: Log features ...)
<button type="button" id="clear-cache">Clear cache</button>

async function clickHandler(event) {
    await cache.clear();
    event.target.disabled = true;
    event.target.textContent = 'Cache cleared';
}

Oops, depends on this: https://github.com/fregante/webext-storage-cache/issues/4

PR welcome for that

Added

<img width="681" alt="" src="https://user-images.githubusercontent.com/1402241/72054359-69b6f700-32fb-11ea-9d54-8de90961cf01.png">

@fregante thanks!

Is clearing on disable still an option? Or you don't see the need?

It sounds like a good idea, but I don't think it's worth the trouble. I'd have to add yet another method on the cache (to get/delete more than one at once) and it's not something that happens that frequently. If your intention is to flush the cache, now there's a button.

There are some more ideas about cache behavior during development, have a look here: https://github.com/fregante/webext-storage-cache/issues/3