On top level click on Sync to get to Sync Settings Page:

(1) “Sync passphrase” should be a link (same as “Learn more” in existing settings: https://support.google.com/chrome/answer/1181035?p=settings_encryption&rd=1)
(2) Click "Encrypt all synced data with your own sync passphrase" under "Encryption options." Add a “Reset sync” link