1203331 - Use SingletonEventManager in a few places

Status: RESOLVED FIXED

(WebExtensions :: Untriaged, defect)

Description

[Bill McCloskey [inactive unless it's an emergency] (:billm)]

I've realized that EventManager is causing a lot of problems. In theory, it consolidates event registration. So if the extension calls addListener 10 times, we only register a real listener once and then notify the add-on 10 times.

Some of our code takes advantage of this behavior by assuming a single callback can be registered per extension rather than having to deal with a Set of callbacks. However, there's a subtle problem with this. The EventManager is does one registration per content, and a given extension can have many contexts (one for the background page, one for a popup, and some for extension tabs). So if you try to register an onAlarm listener in a popup and again in a background page, one of them will be ignored.

Ideally I would convert these to SingletonEventManagers in preparation for bug 1203330. However, SingletonEventManager needs some additional work for that to happen, so I'd like to land this as-is. A number of tests in other bugs depend on it, so this blocks several things.

Comment 1

[Bill McCloskey [inactive unless it's an emergency] (:billm)]

Attachment: patch

Comment 2

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/b83bc163064d

Comment 3

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/14b95ac5262b

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/14b95ac5262b