Chrome Version       : 64.0.3277.0
OS Version: Android
URLs (if applicable) : http://bokand.github.io/demo/urlbarsize.html

What steps will reproduce the problem?
1. Load the above page with mobile emulation in DevTools turned on. Use the Nexus 5X emulation profile.
2. Click the rotate button to bring down a menu for navigation bar options
3. Compare the difference between "Portrait - Default" and "Portrait - Navigation Bar"

What is the expected result?
The orange bars shouldn't change size between default and navigation bar. That is, on a real device, hiding the URL bar doesn't resize them. The viewport-unit bar should be longer than the percentage based one.

What happens instead of that?

Both orange bars are the same size when the URL bar is showing or hidden.