1823670 - MessageHandler modules can still emit events for pages in BFCache

Status: RESOLVED FIXED

(Remote Protocol :: Agent, defect, P1)

Description

[Julian Descottes [:jdescottes]]

Spotted while working on Bug 1822772.

We don't destroy MessageHandlers when a page is moved to BFCache, because the corresponding JSWindowActor is not destroyed. We didn't spot any issue with this earlier because:

• the MessageHandlerRegistry was still only keeping one MessageHandler per session id, meaning it was "forgetting" about the MessageHandler moved in BFCache
• broadcast from the parent process explicitly select compatible browsing contexts and therefore don't try to target contexts in BFCache
• all our content process events were no longer emitted when the corresponding page was moved in BFCache

But since we started using the ChromeEventHandler to monitor load and DOMContentLoaded events, on non-fission the "bfcached" message handlers would still emit events for the "live" pages, resulting in duplicated events.

We should destroy MessageHandlers when their corresponding page is persisted in bfcache (this can either be done by the registry or by monitoring pagehide), and we should reinstantiate them when the page is taken from the bfcache (pageshow event)

Comment 1

[Julian Descottes [:jdescottes]]

Attachment: Bug 1823670 - [messagehandler] Destroy MessageHandlers when pages move to BFCache

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c21b16c9c0d3
[messagehandler] Destroy MessageHandlers when pages move to BFCache r=webdriver-reviewers,whimboo

Comment 3

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/c21b16c9c0d3