> Article 4(1): ‘personal data’ means any information relating to an identified or identifiable natural person (‘data subject’); an identifiable natural person is one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person;
If this chrome browser ID is matched against a (for example) google account, then they can track every single person. And that is just a couple of IDs, let alone all the quantity of data they have.
It's against GDPR to not be clear about this kind of ID. If my browser has an unique ID that is transmitted, then this ID can be coupled with other information to retrieve my identity and behavior, so it should be informed (in the EU).
EDIT: TD;LR, hiding behind "there is no PII in that ID" is not enough.