Added a virtual destructor to get the test to compile on all platforms.
Added a virtual destructor to get the test to compile on all platforms.

BUG=
TEST=

Review URL: https://webrtc-codereview.appspot.com/507003

git-svn-id: 9b397c5dfe384c04b1b200d5305b653241000171@2082 4adac7df-926f-26a2-2b94-8c16560cd09d

lukeweber/webrtc-src-override,lukeweber/webrtc-src-override,lukeweber/webrtc-src-override,lukeweber/webrtc-src-override,lukeweber/webrtc-src-override,lukeweber/webrtc-src-override,lukeweber/webrtc-src-override