An event emitter that should fire when breadcrumbs change for a given URI.
The priority of this breadcrumbs contribution. Contributions are rendered left to right in order of ascending priority.
The breadcrumb type. Breadcrumbs returned by
#computeBreadcrumbs(uri) should have this as
Attaches the breadcrumb popup content for the given breadcrumb as child to the given parent. If it returns a Disposable, it is called when the popup closes.