Add event handling in SharedXDisplay.

SharedXDisplay has to handle X events because the events may belong to
different clients of that class.

R=wez@chromium.org

Review URL: https://webrtc-codereview.appspot.com/2386004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@4953 4adac7df-926f-26a2-2b94-8c16560cd09d
3 files changed