How to run webgl with software rendering on ubuntu 12.04

How to run webgl with software rendering on ubuntu 12.04

My graphics card support OpenGL 1.4 only.
I had download mesalib7.11 and build completed, I can force set a link
mesallvm.so -> libGL.so.1.5.0, then webgl can work fine on Firefox 23.
But I have try "chrome:flag"->Press Ctrl + f and type " Rendering list ",
"Override software rendering list" should come up, Now click on Enable and
restart the browser. The webgl still not working.
Would you please help to tell me how to run webgl with software rendering
on chrome.