debug what's going on with chromium in travis

see https://travis-ci.org/internetarchive/brozzler/jobs/514858838
(unroll "sudo cat /var/log/brozzler-worker.log")

2019-04-02 20:16:01,792 18595 CRITICAL BrozzlingThread:42073 brozzler.worker.BrozzlerWorker.brozzle_site(worker.py:412) unexpected exception
Traceback (most recent call last):
  File "/opt/brozzler-ve3/lib/python3.6/site-packages/brozzler/worker.py", line 379, in brozzle_site
    enable_youtube_dl=not self._skip_youtube_dl)
  File "/opt/brozzler-ve3/lib/python3.6/site-packages/brozzler/worker.py", line 215, in brozzle_page
    browser, site, page, on_screenshot, on_request)
  File "/opt/brozzler-ve3/lib/python3.6/site-packages/brozzler/worker.py", line 292, in _browse_page
    cookie_db=site.get('cookie_db'))
  File "/opt/brozzler-ve3/lib/python3.6/site-packages/brozzler/browser.py", line 341, in start
    self.websock_url = self.chrome.start(**kwargs)
  File "/opt/brozzler-ve3/lib/python3.6/site-packages/brozzler/chrome.py", line 200, in start
    return self._websocket_url()
  File "/opt/brozzler-ve3/lib/python3.6/site-packages/brozzler/chrome.py", line 247, in _websocket_url
    raise e
Exception: chrome process died with status 1

.travis.yml

@@ -16,6 +16,7 @@ install:
 - sudo apt-get update
 - sudo apt-get install --only-upgrade chromium-browser
 - chromium-browser --version
+- timeout 20 chromium-browser
 - sudo svc -t /etc/service/brozzler-worker
 - sleep 10
 - sudo cat /var/log/brozzler-worker.log