Clone the git-repositories listed in //third_party/blimp_fonts/README.chromium, and roll forward to the commit you want.
Copy the necessary files to //third_party/blimp_fonts/font_bundle.
Verify that the fonts.xml file include the correct fonts.
Verify that the LICENSE file is still up to date and lists all relevant licenses and which fonts use which license.
Update the //third_party/blimp_fonts target to include all the current fonts and their license files.
Update the engine dependencies using //blimp/tools/generate-engine-manifest.py. This step is documented in //blimp/docs/container.md.
Run the upload_to_google_storage.py (from depot_tools) script to upload the files. You must do this in the //third_party/blimp_fonts directory. To do this, execute:
upload_to_google_storage.py --archive -b chromium-fonts font_bundle
Add all the font_bundle.tar.gz.sha1 file to the chromium src repository, by executing the following command:
git add ./third_party/blimp_fonts/font_bundle.tar.gz.sha1
Commit and upload the change for review:
git commit
git cl upload