Code of Conduct

We follow the Chromium code of conduct in our our repos and organizations, mailing lists, and other communications.


Install depot_tools.

Then checkout the catapult repo.

git clone

You can then create a local branch, make and commit your change.

cd catapult
git checkout -t -b foo origin/master
... edit files ...
git commit -a -m "New files"

Once you're ready for a review do:

git cl upload

Once uploaded you can view the CL in Gerrit and request a review by clicking the “Start Review” button, and adding a reviewer from the OWNERS file. You can also click the “CQ Dry Run” button to run all the tests on your change.

If you get review feedback, edit and commit locally and then do another upload with the new files. Before you commit you‘ll want to sync to the tip-of-tree. You can either merge or rebase, it’s up to you.

Then, submit your changes through the commit queue by checking the “Commit” box.

Once everything is landed, you can cleanup your branch.

git checkout master
git branch -D foo

Becoming a committer

If you're new to the chromium-family of projects, you will also need to sign the chrome contributors license agreement. You can sign the Contributor License Agreement, which you can do online. It only takes a minute. If you are contributing on behalf of a corporation, you must fill out the Corporate Contributor License Agreement and send it to us as described on that page.

If you‘ve never submitted code before, you must add your (or your organization’s) name and contact info to the Chromium AUTHORS file.

Next, ask an admin to add you (see adding committers)

Contributing from a Chromium checkout

If you already have catapult checked out as part of a Chromium checkout and want to edit it in place (instead of having a separate clone of the repository), you will probably want to disconnect it from gclient at this point so that it doesn't do strange things on updating. This is done by editing the .gclient file for your Chromium checkout and adding the following lines:

'custom_deps': {
    'src/third_party/catapult': None,

In order to be able to land patches, you will most likely need to update the origin remote in your catapult checkout to point directly to this GitHub repository. You can do this by executing the following command inside the catapult folder (third_party/catapult):

git remote set-url origin

Code style

See the style guide.

Individual project documentation

Look to individual project documentation for more info on getting started:


Check individual project documentation for instructions on how to run tests. You can also check the current status of our tests on the waterfall. Use the “Submit to CQ” button in Gerrit to commit through the commit queue, which automatically runs all tests. Run the tests before committing with the “CQ dry run” button.

Updating Chromium's about:tracing (rolling DEPS)

Chromium‘s DEPS file needs to be rolled to the catapult revision containing your change in order for it to appear in Chrome’s about:tracing or other third_party/catapult files. Follow the directions for rolling DEPS to do this.

Adding a new project

Please read the directory structure guide to learn the conventions for new directories.