Add empty files to implement a in-memory DTLS identity store without breaking Chromium build.

BUG=4241
R=pthatcher@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/36199004

Cr-Commit-Position: refs/heads/master@{#8424}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8424 4adac7df-926f-26a2-2b94-8c16560cd09d
7 files changed