Chrome tends to push minor updates (often security) pretty frequently. We'd like to operate as a good member of the Linux ecosystem and just offer an apt/yum/etc. archive, but it seems unlikely to me that people will accept pulling a new 20mb binary package every few days.
One idea I've idly had is that we could provide deltas, ideally ones that would reconstruct the normal packages you'd get if you went through the slow path. For example, it could look at which package version you currently have installed, then combine the diff with the files you currently have installed to regenerate the files that would be in the newer package, and then construct the package from there and hand that off to dpkg/rpm. I've heard about such tools existing but my Googling is failing me. Do you have any links? Do you have any friends I could ask?
(For comparison, Firefox uses its own autoupdate system on Linux if you haven't installed it via a distributor, which is actually pretty reasonable when you consider the above. But this also requires that the running binary have write access over its own files, which more or less means it needs to be installed in your home directory. This is one of the reasons (aside from the fact Microsoft also recommends it) that Chrome on Windows installs into the Windows equivalent of your home directory.)