This is a Chromium issue that also affects Windows 7 (but not Windows 8?). Adding the command line argument --allow-no-sandbox-job fixes the issue, at least under Windows 7. However, there may be some security cost to doing so; see http://peter.sh/experiments/chromium-command-line-switches/. Solution obtained from https://productforums.google.com/forum/#!topic/chrome/skfp2nyNh4o. It would be nice if they removed the need for this workaround.
Another proposed solution (https://forums.opera.com/topic/1799/run-as-different-user) is to use the --no-sandbox argument, but that option would seem to entail a greater loss in security than --allow-no-sandbox-job.