[Bug] App links - custom scheme URLs not reaching the SessionObserver

[jhugman]

This affects logging into slack.

STR:

1. Go to https://api.slack.com/docs/deep-linking
2. Click on Open in slack.

Expected:
The slack app opens.

Observed:
The page reloads.

This is the a-c part of fenix#1213.

┆Issue is synchronized with this Jira Task

[pocmo]

Ah, yeah, probably because they are not actually getting loaded. Does the interceptor see them? Or onLoadRequest() in GeckoEngineSession?

[jhugman]

Both interceptor and GeckoEngineSession.onLoadRequest() sees them. However, this isn't forwarded on to EngineObserver.onLoadRequest().