This is the PDF.js project output,
https://github.com/mozilla/pdf.js
The current upstream commit is documented in the revision field in moz.yaml
To update PDF.js locally, run
./mach vendor toolkit/components/pdfjs/moz.yaml
To avoid cloning PDF.js locally for every invocation of that command, you can
point ./mach vendor at a local repo by setting the PDFJS_CHECKOUT env var.
The update process will perform a git fetch and checkout the latest version to
update to, so any uncommited local changes will cause the update script to break.
