Chrome Version       : 56.0.2924.79
OS Version: 9000.76.0
URLs (if applicable) :
Other browsers tested:
  Add OK or FAIL after other browsers where you have tested this issue:
    Chrome OS can only see one of two monitors attached via a USB C docking station. The issue is especially bad if you're trying to boot and log in while the docking station is connected. 

What steps will reproduce the problem?
1.Attach Chromebook Pixel 2 to HP USB C docking station with two monitors connected
2. Boot up and log in 
3. Only one monitor detected
4. Reboot while docking station is attached can sometimes trigger a long boot (2-3min) 


What is the expected result?
Chrome desktop should be extended to all connected external monitors. 

What happens instead of that?
Only one is visible. 

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

This is the docking station I'm using with the Pixel 2:

http://www8.hp.com/h20195/v2/GetPDF.aspx/4AA6-3246ENW.pdf

UserAgentString: Mozilla/5.0 (X11; CrOS x86_64 9000.76.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.79 Safari/537.36