This could be seen as a technique to undermine Firefox and get more users to Chrome, which would devalue Firefox's contribution to Google. As Google appears to embrace standards but continues to implement little flaws and Chrome-only behaviors (that is, extend), they will eventually deplete Firefox's market share to the point where such a monetary transfer is no longer beneficial (extinguish).

People always bring up the fact that there is some value currently provided by Google's payment to Firefox like there's no problem with the vast majority of the Mozilla Foundation's funding coming from a competing entity. It's still a dangerous situation, even if Google is in a position where they're willing to continue paying the "default search engine" toll for the time being. Even their willingness to do that is compassionate, because we all know that Firefox would only harm itself by switching to another default search provider.