There is an interesting mythology about competing browsers that parallels competing OSes. The "my platform is safer than your platform" argument never seems to abate.

In actuality, the relative safety over time seems to almost perfectly mirror the evolution of living organisms. Whichever one becomes most prevalent then becomes the target of virus writers. If users of Safari or Chrome succeed in winning over a large market share, they too will suffer the consequences of increased attention of the dark side.

It should be noted that Safari will be less likely to be updated than Chrome, because of the difference between Safari's update mechanism and Chrome's silent updater.

So as flaws are found, most Chrome users will be protected by patches, most without the knowledge that a patch has taken place.

Of course this still doesn't protect against severe zero-day exploits.