1597504 - Audit nsIDocShellTreeItem usage in nsWindowWatcher::OpenWindowInternal in toolkit/components/windowwatcher/nsWindowWatcher.cpp

Status: RESOLVED FIXED

(Core :: DOM: Navigation, defect, P3)

Description

[Kannan Vijayan [:djvj]]

In file toolkit/components/windowwatcher/nsWindowWatcher.cpp

Already fission-aware code.

Only uses DocShellTreeItems as a way to get to the corresponding BrowsingContext.

Once nsIDocShellTreeItem uses go away, this code will need to be changed to get the BrowsingContext directly from the window.

Comment 1

[Chris Peterson [:cpeterson]]

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

Comment 2

[Chris Peterson [:cpeterson]]

We need to audit this use of the nsIDocShellTreeItem interface. With Fission enabled, Documents and nsDocShells for related frames, such as subframes and parent documents, may not be available within the current process and the corresponding nsIDocShellTreeItem methods will return null.

If this code is broken with Fission, fixing it blocks enabling Fission is Nightly.

If this code works as-is with Fission, we don't need to remove this usage of nsIDocShellTreeItem until when we remove nsIDocShellTreeItem entirely (bug 1607591) after we ship Fission MVP.

Fission documentation about replacing nsIDocShellTree Item:
https://wiki.mozilla.org/Project_Fission/DocShell_Tree_Replace

:farre's presentation with examples of replacing nsIDocShellTreeItem with BrowsingContext, WindowContext, SyncedContexts, and BrowsingContextGroup:
https://docs.google.com/presentation/d/1K4j6ngty64TZjJNS5qH-MBoOm3TI2dJedVsbH8jUhKE/edit#slide=id.g6e35225e5d_1_264

Comment 3

[Chris Peterson [:cpeterson]]

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

Comment 4

[Chris Peterson [:cpeterson]]

Fixed. This code was rewritten to use BrowsingContext.