web_accessible_resources | messaging Chrome extension from web page | Browser Plugin library

When you use it in a CSS file or code line, try to use it like this:

activeTab works only when the user explicitly invokes your extension as described in the documentation for WebExtensions and Chrome extensions). Evidently, its name is highly misleading: it should have been something like activeTabWhenInvoked.

In order to access any tab without prior interaction with your extension you'll have to add broad host permissions in manifest.json:

The author of an extension lists such accessible resources in its manifest.json intentionally. This is a feature used by extensions to add a UI or a font/image to the web page(s) and so on.

Fingerprinting is possible only due to a poor implementation in Chrome (and Chromium-based browsers), which will be eventually fixed in ManifestV3 so extensions can set use_dynamic_url.

Firefox WebExtensions aren't affected because Firefox uses a unique per-machine UUID, more info.

It turns out that duplicate keys are no longer allowed. And to fix it, you not only need to delete one of the duplicates (as I did), but you need to unpublish your extension entirely and then republish.

It wasn't clear on what would happen when unpublishing. Essentially, you extension will disappear from the Webstore and when you republish, it takes longer than usual to review it. (it took about 2 days vs the normal couple hours). In that time it will say 'pending' but when it does get approved, everything in your store will be restored and it will be as though nothing happened.

Add schema to URL:

Use messages like below

popup.js

Based on your description and the manifest code you provided, and the screenshot shows the "Inspect popup" option is disabled (greyed out), so I think your problem is that there is no "default_popup" declaration in the manifest. Or you can use chrome.browserAction.setPopup to solve the problem.

This is a similar case：Disable "inspect popup" menu entry in chrome extensions.

We can use chrome.runtime.getURL API to get the URL of our resource and then we can provide that URL in src of font-face.

I tried using the Manifest v2 format for web_accessible_resources. It loaded successfully, but it had a background error that said, “The maximum currently-supported manifest version is 2, but this is 3. Certain features may not work as expected.” I guess that solves that. Microsoft's documentation didn't make that clear.