feat(coil-extension): add accept-monetization via declarativeNetRequest

[mankins]

Note this a different approach to https://github.com/coilhq/web-monetization-projects/pull/1910, as suggested in the comments by @sublimator https://github.com/coilhq/web-monetization-projects/pull/1910#discussion_r633034791

This PR proposes the addition of the Accept-Monetization header which follows the Content Negotiation pattern used by Accept, Accept-Language, etc.

If this PR is merged, the following header will be added to web requests from the client:

Accept-Monetization: webmon/*;q=0.8

HTTP servers can then choose specialized content for the client, or issue a content negotiation sequence: a 402 status code followed by user-facing instructions on how they might pay for the site.

More on the Accept-Monetization proposal.

This is opportunistic and doesn't replace the client-side web monetization standard.

This is a signal, not a guarantee. Well behaved clients can get the benefit of individual content without having to wait for detection / complete page load.

Verify / QA

The see this in action you can build the extension and then inspect the outgoing http headers. There should be a new header:

Accept-Monetization: webmon/*;q=0.8

To test how content negotiation might work you can run the express server at Accept-Monetization proposal and visit the pages referenced for web monetization.

maybe they'll make it available in v2 extensions (as google does) in the near term? v3 support seems a long way out still

• [ ] Check when declarativeNetRequest is available in FF manifest v2
  • [x] check FF version 94.0.2
    • 

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[sublimator]

@mankins

Hey, so of course Firefox doesn't support the declarativeNetRequest api/permission :/

It's a pity cause it's a decent API with performance advantages (one assumes at least)

[mankins]

@sublimator I could add back https://github.com/coilhq/web-monetization-projects/pull/1910 into this PR?

I haven't looked into how the different builds happen, but you could branch if the browser has support? Or does this make the proposal DOA?

[sublimator]

Yes, we could make that work! :) I can look into hacking the build for you. I just forgot before its not impl on FF. A pity Mozilla is so against it.

[sublimator]

@mankins I guess you saw this: https://blog.mozilla.org/addons/2021/05/27/manifest-v3-update/

Mozilla are implementing declarativeNetRequest :)

edit: maybe they'll make it available in v2 extensions (as google does) in the near term? v3 support seems a long way out still