UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/51.0.2704.79 Chrome/51.0.2704.79 Safari/537.36

Steps to reproduce the problem:
1. Open Chromium, don't be signed in
2. Click 'Sign in to Chromium' button in settings or in the upper-right corner
3. Switch to another application (e.g. a password manager) by clicking on the task bar or via Alt+Tab

What is the expected behavior?
Sign in dialog stays open after you clicked the 'Sign in to Chromium' until you close it manually or finish signing in.

What went wrong?
Sign in dialog disappears, forgets your inputs, you have to open it again and re-enter your credentials.

Did this work before? No 

Chrome version: 51.0.2704.79  Channel: n/a
OS Version: Ubuntu 16.04.1 (64-bit)
Flash Version: