Add CHECK to EventWrapper to see if there's a subtle bug there or not.

R=pbos@webrtc.org
BUG=

Review URL: https://webrtc-codereview.appspot.com/38039005

Cr-Commit-Position: refs/heads/master@{#8302}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8302 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed