I use a beta version of Google Chrome (latest 15.0.874.81 beta) from official repo (deb http://dl.google.com/linux/chrome/deb/ stable main). I remember it was shipped with Flash, but it worked not as good as I would like it to, so I was using 64-bit betas (not great either, to be honest), IIRC by disabling Chrome's own Flash in about:plugins. Now looking there I see only one Flash plugin, which is the one installed in my system (Location: /usr/lib/flashplugin-nonfree/libflashplayer.so). So even if Chrome's custom Flash is better, as you imply, dunno how to turn it on for a test ride now.
Also
dpkg --contents google-chrome-beta_15.0.874.81-r103858_amd64.deb | grep -i fl