Just because Google gave them $1 billion doesn't mean it impacts their priorities (see: Apple and the rumored billions Google gives them for being the iOS search engine placement). It also matters what other offers are on the table. I bet Microsoft would be willing to pay plenty for Bing placement in Firefox. Both Mozilla and Microsoft clearly considered the possibility seriously (remember Firefox with Bing?).
Also remember that, initially, Firefox's Google contract expired without being renewed. Instead, the renewal came a few weeks later. At the time there was plenty of speculation that Google was letting Mozilla twist in the wind. Considering how much Google came back with, it certainly looks like any twisting went in the other direction.
That's why I said I hope, money does have a way to corrupt things. Sometime it starts as a noble thing: "let's do this one thing because it's a necessary evil..."
(see: Apple and the rumored billions Google gives them for being the iOS search engine placement)
Yeah but Google is trying, hoping and praying to destroy Apple's 50-Billion-in-profit business.
I disagree with your last statement. The most convincing explanation I've seen of Google's motivations with Android is that Android is a hedge in case Google is locked out of other platforms. They make money from people using Google services, regardless of whether the services are used from an iPhone, iPad, or Android device. Google and Apple certainly compete in many areas, but Google isn't trying to "destroy" Apple's business, nor is that even realistic.
Also remember that, initially, Firefox's Google contract expired without being renewed. Instead, the renewal came a few weeks later. At the time there was plenty of speculation that Google was letting Mozilla twist in the wind. Considering how much Google came back with, it certainly looks like any twisting went in the other direction.