Anyone can file bugs and add comments to bugs, but some things—adding labels, marking duplicates, changes status—require extra permissions.
There’s plenty you can do to help with triage without any extra permissions, but if you are doing a lot of triage you can be even more effective if you can edit bugs. Just as with becoming a committer, however, these extra permissions comes with an expectation of responsibility.
First, spend at least a few weeks triaging bugs as described in the triage guidelines, doing the parts that don't require extra permissions and aiming to make significant contributions to at least 20-30 bugs. This is to demonstrate that you are committed to helping triage bugs, that you understand the triage process, and that you can work with the rest of the Chromium community.
Once you’ve done that, email a link to your code.google.com profile to email@example.com (only if you are asking to have your triage history reviewed, not for generic requests about getting an @chromium.org account), who will review your contributions and either provide feedback, or start the formal nomination process. As with becoming a committer, the final decision will be made by the firstname.lastname@example.org list.
A few things to keep in mind while you are getting started with triage, which will help ensure that the nomination process goes smoothly: