Shutdown the embedded webExtension when bootstrap is asked to shutdown

[ianb]

@rhelmer or @6a68

[rhelmer]

lgtm, this is almost exactly what I tested locally.

[jaredhirsch]

@ianb This looks good. Sadly, I think we need to change the "if reason == APP_STARTUP" bit from the startup method--otherwise I think the pref observer will stop working when the addon is upgraded. Would you mind setting a flag when the observer is registered, then checking that flag, instead of the reason constant, inside startup? We always want exactly one listener.

[ianb]

@6a68 I'm not sure I understand. if (reason === APP_STARTUP) only protects appStartupObserver.register() (which seems to unregister itself). But it doesn't stop the rest of startup() from being called, including the pref observer. Unless I miss what you are thinking about here.

[jaredhirsch]

@ianb Ah yeah, you're right! Sorry about that, merging