[w3c/manifest] Add optional Transition Screen member (#478)

To enable progressive web apps to have native-like behavior, a potentially important aspect of functionality is the app or UA being able to display some sort of indication when the user has triggered a navigation.

This optional member would contain an array of images of different sizes that UAs could display between when a navigation is invoked and when the next page is ready to be displayed to the user.  

If this optional member is present, UAs could:
1. Use a platform default (ex: spinner, loading bar, hourglass or watch icon, etc.)
2. Display an image of appropriate size for their screen 

The optional member should also support some "NONE" value so that Web Manifest authors could indicate that they do NOT want the UA displaying any loading indication (as they may already be doing so in their web app.)

---
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/manifest/issues/478