As you know, Google launched an alternative to Pwn2Own to ensure it got the full rights to any sandbox exploitation so when the VUPEN team announced it would arrive here with a Chrome zero-day, the Google Chrome security team decided to set a trap.
Google could figure out very easily if a certain exploit technique was being used. Even more, if an attack targeted third-party (er, Adobe Flash Player) code, they could pinpoint the technique.
In this case, the Google Chrome security knew that the Flash Player plugin sandbox is significantly weaker and that an exploit against Chrome’s Flash Player would have to go through a certain path.
Having figured out that Vupen used that technique (from the May video), Google decided to add a specific protection for Flash.
On March 5, the protection was added to Google Chrome 17.0.963.65. When the protection triggers, it generates a very unique signature — 0xABAD1DEA — which is hexidecimal that spells out "a bad idea". The protection was meant to make the browser resilient to certain attacks but in a bit of cat-and-mouse, it was left in there to see if anyone would find it and make a public comment.
The VUPEN team arrived at CanSecWest and during testing of its exploits for Pwn2Own, they stumbled into the exception.