I've built and run 64-31062 and 66-35902. Revision 64 works fine for me. Revision 66 however does not. I get a load failure with error code -336 (ERR_EMPTY_PROXY_LIST).
In ProxyService::TryToCompleteSynchronously(), revision 66 doesn't call HttpNetworkTransaction::proxy_info_'s UseDirect(). Revision 64 does. I'm not trying to suggest this is the cause of the failure, but rather that it is simply the origin.