Add navigation_ui property (fixes #765).

[mounirlamouri]

Closes #765

This change (choose one):

• Breaks existing normative behavior (please add label "breaking")
• Adds new normative requirements
• Adds new normative recommendations or optional items
• Makes only editorial changes (only changes informative sections, or
  changes normative sections without changing behavior)
• Is a "chore" (metadata, formatting, fixing warnings, etc).

Implementation commitment (delete if not making normative changes):

• Safari (link to issue)
• Chrome (link to issue)
• Firefox (link to issue)
• Edge (public signal)

Commit message: add navigation_ui property

Adds hint in the manifest regarding the visibility of the navigation ui.

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Preview | Diff

[marcoscaceres]

The proposal seems fine... I guess we might want to be a bit more suggestive about what it might include? Like, obviously the ability to navigate back, forward, and reload?

[mounirlamouri]

The proposal seems fine... I guess we might want to be a bit more suggestive about what it might include? Like, obviously the ability to navigate back, forward, and reload?

In practice, at least for fullscreen, this is only used on mobile and it's usually backward and back to homescreen. I'm happy to add some guidance around this to be a bit more specific if that works for you.

[mounirlamouri]

@marcoscaceres ping :)

[g-ortuno]

How does this fit with minimal-ui, #693, and #673?

[mounirlamouri]

The spec suggests that if navigation_ui is set, it should be respected and if it's not set, the default behaviour should be followed. This would apply to minimal_ui as much as to fullscreen or standalone. On mobile, it's likely that a UA would show the navigation bar with minimal_ui but the website could have a way to opt out. Regarding the inconsistencies on desktop, this would offer one more toggle that websites can use to increase consistency and guarantee a certain level of experience.

[marcoscaceres]

This proposal didn't seem to go anywhere. @mounirlamouri, can we close this?

[mounirlamouri]

As far as I know, Chrome is no longer planning in adding this feature. I will close.