WebGL appears to be disabled by default, but for me at least it was possible to get it going by adding the following arguments to the launcher in the apps menu -
--enable-webgl --allow-file-access-from-files --ignore-gpu-blacklist
My Intel/Mesa card appears to be blacklisted, open issue, but so far it seems to work ok.
Looking at chrome://gpu in Chrome I now see:
Graphics Feature Status
Canvas: Hardware accelerated
Compositing: Hardware accelerated
3D CSS: Hardware accelerated
CSS Animation: Software animated.
WebGL: Hardware accelerated
WebGL multisampling: Hardware accelerated
Accelerated CSS animation has been disabled at the command line.
No idea why the CSS acceleration is disabled.
Some relevant refs. I came across: WebGL in Chrome 10 on Ubuntu 10.10 (current is more like Chrome 20, Ubuntu 12.04, but this all seems to still be valid), List of Chromium Command Line Switches, Chrome Experiments.
I'm still a bit mystified by this next thing. After upgrading Ubuntu, I noticed in Ubuntu, System Settings -> Graphics I have:
Driver : Mobile Intel® GM45 Express Chipset x86/MMX/SSE2
Experience : Fallback
Which suggests a fallback driver is in use, yet:
~$ glxinfo | grep render
direct rendering: Yes
OpenGL renderer string: Mesa DRI Mobile Intel® GM45 Express Chipset x86/MMX/SSE2
suggests it's using the correct driver...