Fixes brave/brave-browser#1229 Webtorrent media scaling.

[kylemiller3]

Screenshots of changes:
https://i.imgur.com/Z58xjWr.png
https://i.imgur.com/NRpTmFO.png

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
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  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protection-Mode
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  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection

Test Plan:

Load a video torrent in webtorrent and see it it fills the body of the window in letterbox effect.
Load an image torrent in webtorrent and see the iframe fills the body of the window.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
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After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[bbondy]

Is this still valid? CC @feross

[kylemiller3]

Should still work. Pretty trivial fixes

[feross]

Is there a reason why these styles cannot be applied using CSS?

video {
  padding: 0;
  margin: 0;
}

[kylemiller3]

To be honest it's been so long ago now I don't quite remember if there is a reason or it was just something I overlooked. I believe I did try to use straight up CSS to make it work but I think it needs the media to load first? Something to that effect.

[feross]

Thanks for the PR! I needed to add support for <audio> tags and make some other changes so it was easier to make a new PR: #3005