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Comment by dmtroyer

6 years ago

I must be dense but I never see the `x-client-data` header in the request headers of the network tab in developer tools.

I just checked, I see it on Chrome when fetching resources from google.com, youtube.com, gstatic.com, and googlesyndication.com.

Right-click in the Name column, select "Save all as HAR with content". Then grep for the headers, e.g.,

   sed -n '/headers\":/,/\]/p' example.com.har

While running Chrome, try

   ps ax |grep -o field-trial-handle[^\ ]*[0-9]

Handle to the shared memory segment containing field trial state that is to be shared between processes. The argument to this switch is the handle id (pointer on Windows) as a string, followed by a comma, then the size of the shared memory segment as a string.

Also, can try typing "chrome://versions" in the address bar

https://superuser.com/questions/541466/what-is-the-variation...

https://www.ghacks.net/2013/04/05/field-trials-in-chrome-how...

Further reading:

https://chromium.googlesource.com/chromium/src/+/master/comp...

https://chromium.googlesource.com/chromium/src/+/master/comp...

I just tried it now on google.com, and it sent it in 6 requests. You can ctrl+f in developer tools in Chrome.

It seems that it does not send "x-client-data" header in private mode, but it sends it when browsing regular mode.

  • But unless you changed IP, and other machine characteristics they'll be able to link the machine-id with an alternative fingerprint (cf amiunique/panopticlick).

  • That would mean they are actually not tracking you (via that method at least) in private mode. I was just about to investigate how or if they were tracking in porn mode.