> Google Chrome will automatically send a high-entropy [3], persistent identifier on all requests to Google properties, and this cannot be disabled (X-client-data) [2].
X-Client-Data indicates which experiment variations are active in Chrome:
Additionally, a subset of low entropy variations are included in network requests sent to Google. The combined state of these variations is non-identifying, since it is based on a 13-bit low entropy value (see above). These are transmitted using the "X-Client-Data" HTTP header, which contains a list of active variations. On Android, this header may include a limited set of external server-side experiments, which may affect the Chrome installation. This header is used to evaluate the effect on Google servers - for example, a networking change may affect YouTube video load speed or an Omnibox ranking update may result in more helpful Google Search results. -- https://www.google.com/chrome/privacy/whitepaper.html#variat...
Google doesn't use fingerprinting for ad targeting, through like with IP, UA, etc it receives the information it would need if it were going to. I don't see a way Google could demonstrate this publicly, though, except an audit (which would show that X-Client-Data is only used for the evaluation of Chrome variations.)
(Disclosure: I work on ads at Google, speaking only for myself)
X-Client-Data indicates which experiment variations are active in Chrome:
Additionally, a subset of low entropy variations are included in network requests sent to Google. The combined state of these variations is non-identifying, since it is based on a 13-bit low entropy value (see above). These are transmitted using the "X-Client-Data" HTTP header, which contains a list of active variations. On Android, this header may include a limited set of external server-side experiments, which may affect the Chrome installation. This header is used to evaluate the effect on Google servers - for example, a networking change may affect YouTube video load speed or an Omnibox ranking update may result in more helpful Google Search results. -- https://www.google.com/chrome/privacy/whitepaper.html#variat...
Google doesn't use fingerprinting for ad targeting, through like with IP, UA, etc it receives the information it would need if it were going to. I don't see a way Google could demonstrate this publicly, though, except an audit (which would show that X-Client-Data is only used for the evaluation of Chrome variations.)
(Disclosure: I work on ads at Google, speaking only for myself)