UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2944.0 Safari/537.36

Steps to reproduce the problem:
1. Open DevTools
2. Click on the icon "Toggle device toolbar"
3. Nothing happens
- or: -
2. Press Ctrl+Shift+M
3. The "sign in to Chrome" popup opens instead

What is the expected behavior?
The document window should switch to device mode, as usual

What went wrong?
Nothing happens if the icons is clicked;
If the shortcut is pressed, the user popup gets opened

Did this work before? Yes 

Chrome version: 57.0.2944.0  Channel: canary
OS Version: 10.0
Flash Version: Shockwave Flash 24.0 r0