Can Chrome/Firefox plugins be invoked by random Web Request?

Question

I have a question about plugins in Chrome/Firefox browsers. Is it possible for Chrome/Firefox plugins to be invoked by some random Web Request other than embed or object tags in html?

For example, a page has a web request with MIME jpeg, the browser captures the downloaded raw image data and sends the data to a newly created plugin instance. Is this scene I describe here possible?

Answer 1

Plugins are used:

• with the mentioned object/embed tags
• as handlers for full page content (e.g. seen with PDFs)

Outside of those scenarios, plugins are not used to handle any content/requests.

Answer 2

Some proxy plugins have did what you want, such as FoxyProxy, Proxy SwitchySharp, etc.