I changed the way Kerberos works in >=www-client/chromium-15.0.865.0.
If you're interested in testing, please emerge that version with USE="kerberos" and see if the Kerberos support works as intended. It'd also be nice to test with various Kerberos implementations (MIT vs Heimdal).
Even if you're not using Kerberos, if something is broken in that version please also file bugs.
The changes implemented in that version should make it work better with revdep-rebuild (the browser binary now explicitly links with Kerberos libraries instead of using dlopen, and it uses system headers instead of some modified bundled copy; this way breakages should be fixable by revdep-rebuild and not silent).