There is a rotation of people who are tasked with helping maintain a healthy flow of versions of Chrome/Chromium into ChromeOS/ChromiumOS.
Chrome on ChromeOS Gardening Duties:
1. Shadow Chromium sheriffs for ChromiumOS-specific configurations.
2. Keep ChromeOS UI BVTs green.
3. Help fix the crashes labeled TreeCloser on the Chromium waterfall.
Chrome on ChromeOS gardening documentation