The latest stable build of Google Chrome for Mac has added a series of patches designed to help users transition to Mountain Lion. These stable builds are put out roughly every six weeks, but the latest one is a sign that Google is preparing for the OS that will be coming to machines this summer. In addition to the patches, it now uses Version 11.3 of Adobe Flash Player. The update should install automatically for current Mac users; first-time downloaders can find it here.
This change comes shortly after Google announced a Metro-optimized version of its browser for Windows 8. This isn't nearly as big a change, but it's another move towards the new generation of operating systems. Likewise, though this version should be pretty stable compared to the more experimental Windows 8 build, you can file a bug report over here.