To enable flash you will need to add –enable-plugins to your shortcut command.
You can do this via System > Preferences > Main Menu > Internet > Google Chrome > Edit and adding the above flag at the end of the text in the command field, making sure to leave a space before you add the flag. You can alternatively run the following from a terminal to launch Chrome.
You can also enable extensions by adding –enable-extensions to your shortcut/launch command.
Here is a link to a previous post where i list some of my favourite Chrome Extensions â€” including an all important ad-blocker!
thanks to Sharkbait