Earlier quoted context omitted.
But Chrome is paying more as a percentage of their browser units' income, no? Virtually all of Mozilla's income comes from the browser (via the Google search agreement). The vast majority of Google's revenue comes from ad revenue on search, YouTube, and Adsense. Not from Chrome directly. So they had less incentive to reward its security, but did so anyway. And they also do some of the best work in the industry, free,…
The browser totally has zero to do with google ads. Totally no connection at all.
Personally I believe that the browser is intended to defend against e.g. Facebook's apps. Google wants to make sure that if you buy a new device and it comes with a Facebook app preinstalled, it also comes with a browser. And that the browser isn't controlled by anyone who'd like to disrupt any of Google's many nice income streams.