ChromeOS Build 8743.83.0, 54.0.2840.93

What steps will reproduce the problem?
(1) sign in with dual monitor connected 
   - DP via HP ZR24w 
   - HDMI via Acer FT200HQL 19.5-inch HD 1600x900 touch screen monitor 
(2) Unplug both moniors ( the order does not matter ) 
(3) Plug DP monitor 
    -wait until it comes up with display 
(4) Plug HDMI monitor 

What is the expected output?
Both monitor should come up with display 

What do you see instead?
HDMI monitor never come up with display 

Always reproducible for Acer monitor no matter in mirror or extended mode 
30 seconds delay for HP Z27n-HSTND-6071Q monitor 
It's not reproducible if plug HDMI monitor first, then DP 

Feedback report:
http://feedback/#/Report/15167963225