Test Case for Chromium bug 837185

1. Trigger Protocol and notice that Chrome does nothing at all because the protocol is unregistered
2. Register an external protocol, eg chromiumtest10:// and point it at notepad.exe
   
   • Either, download and run pre-prepared register.reg file to create the protocol,
   • or follow instructions at docs.microsoft.com to create it manually by editing the registry
3. Trigger Protocol again (identical to step 1)
4. Tick "Open these types of links in the associated app"
5. Click "Open Notepad" and notice that Notepad opens
6. Unregister the protocol
   
   • Download and run pre-prepared unregister.reg file,
   • or delete the registry keys you manually created following the Microsoft guide
7. Trigger Protocol again (identical to step 1)
8. Notice that a Windows "You'll need a new app to open this" dialog appears, which is inconsistent with the results of step 1 where the protocol was unregistered: