Today, we’re announcing the end of Chrome’s support for Windows XP, as well as Windows Vista, and Mac OS X 10.6, 10.7, and 10.8, since these platforms are no longer actively supported by Microsoft and Apple. Starting April 2016, Chrome will continue to function on these platforms but will no longer receive updates and security fixes.

Source: Google Chrome Blog: Updates to Chrome platform support

Snow Leopard (10.6) is the Windows XP of the Mac world in many ways. A surprising 10% or so of Mac users are still using it and presumably unable to upgrade, either because they are using an early 32-bit Intel Mac or are using a 64-bit Mac that Apple decided not to support with Mavericks (10.9). (This includes most polycarbonate MacBooks and other models, including those without enough RAM.) If you are running a version of OSX before 10.9, the simplest way to ensure continued support would be to switch to Firefox. (You could also use Windows or a flavor of Linux, both of which would provide a supported version of Chrome on older Mac hardware, but that does mean leaving OSX behind.)

It’s unfortunate that Google is dropping Chrome support, and that Apple left particular Macs behind, especially since some older Apple models will run 10.11 just fine. I find it ironic that Microsoft Windows still supports the same hardware that Apple has abandoned, as it could have run OSX 10.9.