Ok, that guy just explained what he meant by keylogging. Leaving aside the fact that he's wrong about how it all works (the results are provided by Google; nothing about the search was changed by the extension) and he never ever looked at the source code and what it is doing (probably because he's too dumb to understand any of it), what he means by keylogging is adding the search terms to the URL query string when clicking on a link. (Ex: www.ecosia.org/url?url=http%3A%2F%2Fmicrosoftstore.com&v=microsoft store <- this italic text right here is the result of the keylogger in his opinion)

https://productforums.google.com/forum/#!msg/chrome/mlAD1ygc...

So, this is what caused all this shit storm...