One of the major changes to Chrome 34 is support for responsive images, which comes down to a "srcset" attribute for image tags that lets the browser select the image that matches a device's form-factor/capability, such as different image versions for desktops, phones / tablets, or other devices.
Chrome 34's other big addition is that the Web Audio API support is no longer prefixed with the web audio spec now being in line with the W3C draft specification. Other Google Chrome 34 stable changes include new app/extension APIs, support to import supervised users on new computers, and lots of internal changes -- including stability and performance enhancements. There were also 31 security fixes for Chrome 34.
More details on Google's Chrome 34 web-browser can be found via the Google Chrome Release Blog.