The tests started a few weeks ago and, it seems, are advancing rapidly: Google today announced that version 38 of Chrome, now on the beta channel, already 64 bits on Macs.
Anyone who wants to can download and run this version, but those who prefer something more "round" should hold the ends for about six weeks, on average until Chrome 38 reaches the stable channel and is officially launched for everyone. That is, this should occur between the end of September and the beginning of October.
According to Google, Chrome 64-bit will provide performance gains and a reduction in the use of memory, in addition to greater security in the use of the browser. 32-bit NPAPI plugins will obviously no longer work on it, but on the other hand finally the current version of Java (used by most Brazilian internet bankings), which 64 bits, will start to work well on Chrome.
In addition to this great new feature for OS X users, Chrome 38 will also come with a new interface for changing user profiles and entering incognito mode, a new Guest mode (Guest) experimental and general improvements in stability / performance. The specific news for developers was detailed by Google in this post from Chromium Blog.
Update · 09/10/2014 s 23:59
Google today released a new test version of Chrome 38 and apparently 64-bit on Mac, it will only stay for version 39. Apparently, the tests may not have progressed as expected and the company should want to better polish the new architecture before putting it on the stable channel.