Brave should not intercept non-navigation .torrent file requests

Description

If a web page embeds the WebTorrent client-side JS library and attempts to load a .torrent file using an XHR request or fetch, Brave will intercept the .torrent file load and replace it with the chrome-extension HTML, breaking the site. This is true not just for the WebTorrent JS library but for any request to fetch a .torrent file.

There’s a CodePen that demonstrates this here: https://codepen.io/yciabaud/pen/XdOeWM

Steps to Reproduce

1. Visit https://codepen.io/yciabaud/pen/XdOeWM
2. The torrent demo should fail with an error in the console.
3. Now, disable the WebTorrent extension in Brave settings.
4. The demo now works.

Actual result:

Uncaught Error: Error downloading torrent: XHR error
    at VM37 webtorrent.min.js:5
    at t.exports.<anonymous> (VM37 webtorrent.min.js:7)
    at t.exports.t (VM37 webtorrent.min.js:5)
    at t.exports.r.emit (VM37 webtorrent.min.js:4)
    at XMLHttpRequest.c.onerror (VM37 webtorrent.min.js:7)

Expected result:

Brave should not intercept requests for .torrent files unless they are top-level navigation requests.

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Version 0.66.101 Chromium: 75.0.3770.142 (Official Build) (64-bit)

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes
• Can you reproduce this issue with the beta channel?
• Can you reproduce this issue with the dev channel?
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

[kjozwiak]

Verification PASSED on macOS 10.14.6 x64 using the following build:

Brave	0.69.126 Chromium: 77.0.3865.65 (Official Build) (64-bit)
Revision	87a331a3169cab563505fb44011058b904011ba1-refs/branch-heads/3865@{#726}
OS	macOS Version 10.14.6 (Build 18G95)

• ensured that https://codepen.io/yciabaud/pen/XdOeWM works when WebTorrent is both enabled and disabled as per https://github.com/brave/brave-browser/issues/5361#issuecomment-532529740

Verification passed on

Brave	0.69.127 Chromium: 77.0.3865.75 (Official Build) (64-bit)
Revision	201e747d032611c5f2785cae06e894cf85be7f8a-refs/branch-heads/3865@{#776}
OS	Ubuntu 18.04 LTS

• verified that https://codepen.io/yciabaud/pen/XdOeWM works when WebTorrent is both enabled and disabled as per https://github.com/brave/brave-browser/issues/5361#issuecomment-532529740

Verification passed on

Brave	0.69.128 Chromium: 77.0.3865.75 (Official Build) (64-bit)
Revision	201e747d032611c5f2785cae06e894cf85be7f8a-refs/branch-heads/3865@{#776}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• verified that https://codepen.io/yciabaud/pen/XdOeWM works when WebTorrent is both enabled and disabled as per https://github.com/brave/brave-browser/issues/5361#issuecomment-532529740

[feross]

@kjozwiak Yep, this is expected behavior. This is JavaScript code running on the website itself and has nothing to do with the built-in WebTorrent implementation in Brave. It’s supposed to work in both cases – when the WebTorrent extension is enabled or disabled.