1587425 - Fix usage of nsIDocShellTreeItem in nsContentUtils::SetFocusInner

Status: NEW

(Core :: DOM: Navigation, defect, P2)

Description

[Kannan Vijayan [:djvj]]

https://searchfox.org/mozilla-central/rev/7cc0f0e89cb40e43bf5c96906f13d44705401042/dom/base/nsFocusManager.cpp#1190

This accesses a bunch of state that needs to be synchronized to BrowsingContext, namely:

DocShell->IsInUnload
DocShell->IsBeingDestroyed
DocShell->IsInActiveWindow

None of these fields should be mutated heavily, and synchronizing this state should not be too much of an overhead.

Comment 1

[Chris Peterson [:cpeterson]]

Kannan says replacing nsIDocShellTreeItem calls should block enabling Fission in Nightly (M6).

Comment 2

[Nika Layzell [:nika] (ni? for response)]

I don't think we need to sync those particular fields onto the BrowsingContext object. We can probably get away with a less precise mechanism in the cross-process case.

ni? :hsivonen, as this is related to his work with focus when Fission is enabled.

Comment 3

[Henri Sivonen (:hsivonen)]

The main reason to keep using nsIDocShellTreeItem for the focus code in chrome process is that there's intentionally no way to walk from a content BrowsingContext up to a chrome BrowsingContext, but the focus code in the chrome process, IIRC, wanted to walk from a content nsIDocShellTreeItem up to a chrome nsIDocShellTreeItem.

Comment 4

[Chris Peterson [:cpeterson]]

Auditing whether this use of nsIDocShellTreeItem breaks when Fission is enabled blocks Fission Nightly.