Fix compile error on JDK 1.7.

JDK 1.7 gives an error like this:
warning: [static] static method should be qualified by type name

R=pbos@webrtc.org
TBR=henrike@webrtc.org
BUG=

Review URL: https://webrtc-codereview.appspot.com/29399004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7133 4adac7df-926f-26a2-2b94-8c16560cd09d