If I explicitly tell IE (still using IE8 in-house) to use GCF with the gcf prefix Chrome is activated. Downside is any links internal to the target site loose the gcf prefix thereafter. Expected.
Added X-UA-Compatible in the HTTP in Apache of "IE=edge,chrome=1". GCF is never activated. Think this is a general problem with our packaged version of IE8. It seems to ignore all X-UA-Compatible directives.
Wondering if anybody has ran into the same issue? Or if there are log files I can look at? Or increase debugging?
Turns out the "Enable third-party browser extensions" options was blocking GCF from activating. Got super help from Greg Thompson is this Google Forum post:
Went through the back door with gpedit to change up the Admin template and it worked. Still unsure why the compatibility mode for IE isn't working as expected. But at least got GCF going. Thanks again to Greg!