Chrome Version       : 51.0.2704.84
OS Version: Arch Linux (x86_64)
URLs (if applicable) : https://github.com/systemd/systemd/issues/1615
Other browsers tested:
  Add OK or FAIL after other browsers where you have tested this issue:
     Safari 5: FAIL
  Firefox 4.x: OK
     IE 7/8/9: FAIL

What steps will reproduce the problem?
1. Run chromium
2. Open a few tabs/websites
3. poweroff

What is the expected result?

The system shutdowns cleanly and quickly.

What happens instead of that?

After I run poweroff on a terminal, the system shutdowns but it hangs for 90 seconds, I believe this is due to chromium inhibiting the shutdown process.

If I disable "Continue running background apps when Chromium is closed" under System this problem is solved, and my system shutdowns in no time.

Please provide any additional information below. Attach a screenshot if
possible.

UserAgentString: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.84 Safari/537.36