Steps to reproduce the problem:
1. Have a PWA installed from Chrome Beta as WebAPK. The PWA should have a back button in standalone mode which calls history.back(). (or just do that from console)
2. Share a link to that PWA in some app which opens links in "Chrome Custom Tab" (I have no idea how it's named correctly)
3. Tap that link and open in Chrome Beta
4. Chrome Beta opens installed PWA instead and it displays back button (if any)
5. Clicking on the back button has no effect

What is the expected behavior?
It should perform normal stack back action for the app and previous application should be displayed.

This works fine if you tap on a device's back button. 

What went wrong?
Nothing happens when clicking on back button in the PWA.

Did this work before? No 

Does this work in other browsers? N/A

Chrome version:   Channel: beta
OS Version: 
Flash Version: 

This works fine if you tap on a device's back button.