[_phaq]

Actually consented, as in understood the implications and freely decided that Google should have this data, probably none. That would take a lot of generosity, especially to pay that team of lawyers and technical experts, so that you have any chance of actually understanding the implications.

Unwillingly consented, that's the vast majority of Chrome Sync users. Unless you enable the end-to-end-encryption (for which they require a second passphrase, so probably less than 0.1% actually use that), they will use your data for ad profiling etc.. Yes, that is on page 1312 of the Chrome Sync privacy statement. (They're only required to write it into there, if they do it, so it is quite certain that they didn't just want the bad PR for nothing.)

Is consent required? Assuming they actually do collect this data from their Chrome Sync data or through similar personally identifiable ways, consent would be required in many jurisdictions, especially the EU.

However, if they cared enough, it would be possible for them to collect this particular data point without personal identification. You could for example create a UUID per installation that's only associated with this one data point. Or you could have a time-based solution where each Chrome instance goes out to "vote" for their default search engine e.g. every 4 weeks. If you then look at the statistics on a weekly basis, you can just take these values times 4 to even roughly correct numbers. It's certainly going to be representative enough, you don't need every browser instance to have their vote in every week's statistic.

[londons_explore]

Look at the linked patch.

These metrics are from UMA stats. They are collected from everyone who ticks the box to report stats when installing Chrome.

They only get histograms of counts of visits to search engines, not the entire URL, and not search engines or other sites not in the list of things they track (which is at the bottom of the file).

[3xblah]

It is ticking that box I was wondering about. How many users tick it?

chrome://chrome-urls/site-engagement

and other chrome-urls

These can provide useful data for me but not sure why I would want send the data to Google.