This message is pretty common. We'll need to figure out the most common message manager messages going through PContent and figure out how they should be labeled. We may need to add a new mechanism for labeling them. Some should probably be SystemGroup-labeled and others could be moved to the browser message manager (which is already labeled).

Does it have to be labeled with anything more precise than SystemGroup? I don't think the message manager messages can have content-observable effects...can they? Or is the worry that they're going to race with chrome things somehow?

(In reply to Nathan Froyd [:froydnj] from comment #1) > Does it have to be labeled with anything more precise than SystemGroup? I > don't think the message manager messages can have content-observable > effects...can they? They definitely can. Click-to-play, for example, is largely written in JS and uses the message manager to activate and deactivate plugins. Or session restore, which populates form fields based on message manager messages.