Stop timer in ~EventWindows().
Stop timer in ~EventWindows().

Running out of handles seems to have been an issue when adding another
test target, this should solve it.

BUG=
R=mflodman@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2339004

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: c0167702d3db7acb76933db4a3deda281705518a

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc