This indicates an attack attempt against a Clickjacking vulnerability in Google Chrome.
The vulnerability is caused by an error when the vulnerable software handles a malformed html with Cascading Style Sheets (CSS) opacity property. It allows a remote attacker to trick the user into pressing the "Allow" button in the Flash Player settings window via a crafted web page.
Google Chrome before 27.0.1453.116
Information Disclosure: Remote attacker can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.