Should record:

- When registerProtocolHandler is called by a website, whether it was called from a user gesture, and the outcome: {User gesture -> prompt -> allowed, User gesture -> prompt -> blocked, User gesture -> prompt -> prompt closed, User gesture -> was already blocked, User gesture -> was already registered, Non-user-gesture -> Added page action icon, Non-user-gesture -> Was already registered}.
- When the page action icon is clicked (non-modal dialog) and its result: {Allow, Deny, Ignore}.
- When the user changes the default in settings.
- When the user unregisters a handler in settings.