Use the Content Settings dialog to manage the following settings: cookies, images, JavaScript, plug-ins, pop-ups, location sharing, and notifications. Follow these steps:
Click the wrench icon on the browser toolbar. Mac users: If you don't see the wrench icon, go to the menu bar at the top of your screen and click Chrome. Select Options (Preferences on a Mac). Click the Under the Hood tab. Click Content settings in the "Privacy" section. Click the tabs to manage different settings: ... Plug-ins are used by websites to enable certain types of web content (such as Flash or Windows Media files) that browsers can't inherently process. They're allowed by default.
Aparentemente, os desenvolvedores do Chrome mudou as coisas ao redor para que a opção tenha que ser ativada a partir da página about:flags (digite no seu navegador e aperte enter - a parte inferior da tela é "Click-to-play"). Então você ainda pode precisar fazer o procedimento acima.