1066763 - Add a protocol for sending FrameMetrics over IPC so we don't keep so many duplicate copies of it

Status: RESOLVED WONTFIX

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

Description

[Kartikaya Gupta (email:[e-mail])]

As of bug 967844 we can have multiple layers associated with a FrameMetrics (and multiple FrameMetrics on a layer) and since the FrameMetrics class is pretty big (and growing) it would be a nice optimization to not keep sending this data structure over the IPC channel as often.

This is something Matt suggested back in bug 967844 comment 50 but I deferred to later in the interests of getting stuff landed. However this is definitely something we should do.

Also it might be worth renaming FrameMetrics to ScrollMetrics or something, and maybe trying to carve it up into smaller classes because it gets passed around a lot, with a bunch of users only needing a few fields from it.

Comment 1

[Kartikaya Gupta (email:[e-mail])]

In the WebRender codepath we do this, by deduplicating the metrics in the WebRenderScrollData here. I'm not sure it's worth trying to implement this for the non-WebRender codepath since the plan is to transition everything to WebRender eventually.