Steps to reproduce the problem:
1. Add an app to homescreen with enhanced A2H (web APK). For example, twitter.com
2. Inside web APK app, navigate to different url within app such as "notifications"
3. Without closing app, view homescreen and tap twitter icon again

What is the expected behavior?
I'd expect to just switch back to app with notifications page still up.

What went wrong?
It switches back to Web APK app, but switches the page back to the `start_url`

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 58.0.3029.33  Channel: beta
OS Version: 7.1.1
Flash Version: 

There's another, seemingly similar problem, which is why I noticed this to begin with.

I'm building an app that uses passwordless login. Everything works fine when just in the browser, but the emailed "magic auth link" correctly opens the web APK version of the app, but always shows the `start_url` when opening rather than respecting the URL link that it was actually sent to. The strange thing is... the login process still works! It's almost as if it processes the URL with the token in it, but then switches the UI back to the `start_url`.

Sorry I don't have a reduced test case, but I think the Twitter example works fine for demonstrating the basic issue. 

The exact same issue also causes problems when I initiate Stripe checkout from within the app (which opens in a new tab on mobile) then when it redirects back after gathering payment info from the other tab, it again "works" but switches back to the `start_url`.