Also: Microsoft’s financial foundation is in business dependence on Office (and Exchange / Outlook, and Sharepoint)–even more so than Windows. Google is competing against this directly with Google Apps / Docs (and Gmail, etc.). So, Google having a browser optimized to make it’s own Apps “even more better” than Office would pay for itself. Even more better means, in the business context, something like: offline access, configuration for security policies, group / collaboration features, portability (across desktops) and mobile integration.
The open source aspect of Chrome also would drive similar optimizations in Safari and Firefox. Ultimately, one could imagine some significant percent of Office income going to pay for Google Apps for business use on Chrome / Safari / Firefox. And, then, independence from Office also means, in many cases, freedom from Windows, too.