I need to block Flash plugin by default and only allow it on manually approved sites, while allowing the PDF plugin to run anywhere automatically. Is it possible to achieve?
Honestly, my knowledge of permissions in Chrome is a bit... lacking. This sounds like something that should be done in your firewall... and not at a workstation level. In most firewall appliances, it's fairly easy to block certain mime-types & such on-the-fly and white-list some sites. The advantage to this approach is that even if a user switches to IE, Opera, Firefox or whatever else to access whatever annoying flash site... they're still unable to get there.