The main waterfall (https://chromium-build.appspot.com/) is policed by sheriffs to keep it green as possible. When adding a new test to these bots, it's important that the tests be free from flakiness and that the Try Server and CQ provide developers coverage for the test. See the design of the Chromium Commit Queue for details on how this works. Please coordinate with the Infra team and troopers while adding these tests.
Put the test on the chromium.fyi and tryserver.chromium master.cfgs for the platforms that make sense for the test. Watch these tests and eliminate any flakiness that arises.
When the test has been declared stable, it's time to land it on the main waterfall. As these parts depend on each other, try to land all the following simultaneously (with a trooper's help):