This is with the latest xfce 14.04 on Ubuntu 14.04 patched upto today: Xubuntu 14.04.1 LTS, Chromium Version 37.0.2062.120 If you have focus of the browser and then lock and unlock the desktop the browser crashes. Same problem with the latest version of the Chromium web browser.
Sorry this hear this is happening to you, however Xfdesktop doesn't do anything with suspend/resume. That being said, you may have better luck getting a good backtrace and either providing it to Chromium or the Xubuntu developers. http://docs.xfce.org/contribute/bugs/start#backtraces Might be helpful. Let me know if there's more I can do to help you.
Marking as not a bug in xfdesktop.