I just upgrade from 12.04 to 14.04 and for some reason chromium installed as aura. I tried purging it and reinstalling but am still get it.
Chromium has been using Aura since version 35 and has removed most of the GTK code in the M36 (or was it M37?) branch. Ubuntu enabled Aura early in version 34.
The last non-Aura version of Chromium in Ubuntu was version 33, which leaves Chromium 18 in Precise and Chromium 25 in Lucid as the only non-Aura versions.