Back up your data!
Before you switch, you should make a backup of your profile (bookmarks, most visited pages, history, cookies, etc). If you ever want to switch back to a more stable channel, your updated profile data might not be compatible with the older version.
Make a copy of the User Data\Default directory (for example, copy it to ‘Default Backup’ in the same location). The location depends on your operating system:
Windows XP:
- Stable, beta, and dev channels: \Documents and Settings\username\Local Settings\Application Data\Google\Chrome\User Data\Default
- Canary builds: \Documents and Settings\username\Local Settings\Application Data\Google\Chrome SxS\User Data\Default
Windows Vista or 7:
- Stable, beta, and dev channels: \Users\username\AppData\Local\Google\Chrome\User Data\Default
- Canary builds: \Users\username\AppData\Local\Google\Chrome SxS\User Data\Default
Mac OS X:
- Stable, beta, and dev channels: ~/Library/Application Support/Google/Chrome/Default
- Canary builds: ~/Library/Application Support/Google/Chrome Canary/Default
Linux:
- ~/.config/google-chrome/Default
Note: If you’re using Explorer to find the folder, you might need to set Show hidden files and folders in Tools > Folder Options… > View.
Source: http://dev.chromium.org/getting-involved/dev-channel