Sending a PDF to Annotate from another app does not work

[Semphriss]

Reproduction steps

1. Open an app that exports PDF files.
2. Attempt to share a PDF document to Annotate from that app.

Expected

Annotate opens the document.

Actual

Annotate opens, but does not load the document

Additional notes

Webapps don't support the Content Hub very well. Importing/exporting works with HTML features, but importing on request of another app is apparently not supported. This will probably be fixed with #1.