So looks like we're racing between BrowserParent::ActorDestroy and WindowGlobalParent::RecvUpdateSessionStore. I wonder if it would be fine to wait for another event loop in [BrowserChild::DelayedDeleteRunnable](https://searchfox.org/mozilla-central/rev/79d73b4aff88dd4a0f06dd3789e1148c49b0de60/dom/ipc/BrowserChild.cpp#228-230,258-263).
Bug 1703692 Comment 12 Edit History
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So looks like we're racing between BrowserParent::ActorDestroy and non-toplevel WindowGlobalParent::RecvUpdateSessionStore. I wonder if it would be fine to wait for another event loop in [BrowserChild::DelayedDeleteRunnable](https://searchfox.org/mozilla-central/rev/79d73b4aff88dd4a0f06dd3789e1148c49b0de60/dom/ipc/BrowserChild.cpp#228-230,258-263).