There are a couple other points, though:

- Chrome is only available for Windows ATM. Windows boxes are apparently more difficult to crack than Macs.

- Chrome runs in a sandbox, unlike IE or Safari, which adds some security as well.

Chrome sandboxing doesn't rely on things like address space randomization and NX, so the Mac vs. Win32 different --- while probably still present --- may be less pronounced.

Comparing mobile browsers they ignored Opera - the most common mobile browser and the most secure.

I have no idea why you think Opera is the most secure mobile browser.

Do you think it's more common than safari on iphone? Do you have any way to verify that?

Opera Mobile has significantly more installs than Mobile Safari, but Safari probably has greater market share in terms of mobile visits (because iPhone users use Safari quite a bit).

As for numbers, Opera says there are more than 120m installations of Opera Mobile:

http://www.opera.com/mobile/

They have another product, for less powerful phones (it does rendering via a proxy actually) that has 20 million users. Since the requests are all proxies, Opera knows how many people use this product:

http://www.opera.com/mini/

Safari Mobile is also on every ipod touch. giving it an even wider user base.