Why a Google browser ?

I agree with Nicholas Carr that states :

To Google, the browser has become a weak link in the cloud system - the needle's eye through which the outputs of the company's massive data centers usually have to pass to reach the user - and as a result the browser has to be rethought, revamped, retooled, modernized.

Its real goal, embedded in Chrome's open-source code, is to upgrade the capabilities of all browsers so that they can better support (and eventually disappear behind) the applications. The browser may be the medium, but the applications are the message.

Also Google may want to switch from being a pure advertising profit company to a more mathematical algorithmical reality. This is the foundation of the company and I think Larry and Sergey see themselves more as engineers rather than marketeers.