1325945 - Fix crash in WebRenderImageLayer::GetAsSourceSurface, re-enable skipped reftests

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P3)

Description

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

I fixed a memory leak that was preventing WebRender*Layer objects from getting cleaned up, in bug 1325678. However that exposed crashes in two reftests:
  layout/reftests/css-animations/background-position-running.html
  layout/reftests/css-animations/background-position-important.html
so I marked those tests skip-if(webrender). The crashes can be see in the try push at [1]. In particular, the crash stack seems to show that when WebRenderImageLayer::GetAsSourceSurface() is called, |mContainer| is null, and so the AutoLockImage RAII object creation results in a null pointer deref. I don't know if bug 1325349 will fix this but it seems related.

This bug is specifically for making sure the two tests don't crash and can be re-enabled.

[1] https://treeherder.mozilla.org/#/jobs?repo=try&revision=1636a5dbbe8a443ba07d7edd9cf2022978cc7597

Comment 1

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

A null guard seems to do the job: https://treeherder.mozilla.org/#/jobs?repo=try&revision=0508706eb3c1d220a7e10c885f58f45222239798

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/projects/graphics/rev/6c3ac2b72d2b
Guard against possible null pointer dereference. r=sotaro?
https://hg.mozilla.org/projects/graphics/rev/96716340bdf3
Re-enable a couple of tests that were skipped for crashes. r=sotaro?