1714717 - With fission enabled, stop setting zero-margin display ports on async scrollable ancestors (rely on the minimal displayports instead)

Status: NEW

(Core :: Panning and Zooming, task, P3)

Description

[Botond Ballo [:botond]]

In bug 1675547 and dependencies, we introduced "minimal displayports" and started setting them on all scroll frames in Fission mode (which was needed for hit-testing correctness).

That means we shouldn't need the SetZeroMarginDisplayPortOnAsyncScrollableAncestors operation (and its counterpart ExpireDisplayPortOnAsyncScrollableAncestors) in Fission mode any more, since the minimal displayport should serve the purpose of the zero-margin displayport (which is "make sure the ancestor has an APZC for scroll handoff purposes") well.

This bug tracks not using these operations in Fission mode.

Comment 1

[Botond Ballo [:botond]]

As mentioned in bug 1698693 comment 6, I don't think this needs to block any Fission milestone (unless there's a "cleanup" milestone or something like that), because the current state (where SetZeroMarginDisplayPortOnAsyncScrollableAncestors will set a zero-margin displayport on in-process ancestors, while leaving out-of-process ancestors with a minimal displayport) should be harmless.

Timothy, please let me know if you agree.

Comment 2

[Timothy Nikkel (:tnikkel)]

Yes.

Comment 3

[Chris Peterson [:cpeterson]]

(In reply to Botond Ballo [:botond] from comment #1)

As mentioned in bug 1698693 comment 6, I don't think this needs to block any Fission milestone (unless there's a "cleanup" milestone or something like that)

In that case, tracking for Fission Milestone "Future".