I've been battling with this issue for a couple of months now, ever since I upgraded to Ubuntu 10.04 on my main desktop machine. Google Chrome would constantly max out one core, with no indication of what it was doing, or why.
Today, I finally solved the issue. It turns out that something to do with the
m4 package was causing the error, with the following output:
MozPlugger: Error: Failed to execute m4. Mozplugger: M4 parsing of config generated error
So, I checked out the package in question, and found that it wasn't installed.
To my great relief (and some frustration), a simple
sudo apt-get install m4
fixed the problem instantly.
I only hope that this post solves this extremely annoying issue for someone else.