After my fixes for bug 1459686, there are still errors with "Unknown pipline used for iframe blah blah blah" that I can reproduce while running reftests. Investigation showed that we're deleting the pipeline at [1] which happens just before the SetDisplayList call at [2] but in a different transaction. So at the time we delete the pipeline, the display list that WR has for the content is still referencing those pipelines, which is why we get this error. [1] https://searchfox.org/mozilla-central/rev/b28b94dc81d60c6d9164315adbd4a5073526d372/gfx/layers/wr/WebRenderBridgeParent.cpp#767 [2] https://searchfox.org/mozilla-central/rev/b28b94dc81d60c6d9164315adbd4a5073526d372/gfx/layers/wr/WebRenderBridgeParent.cpp#655

Comment on attachment 8973878 [details] Bug 1459714 - Make WebRenderBridgeParent::ProcessWebRenderParentCommands callers provide the transaction. https://reviewboard.mozilla.org/r/242240/#review248136

Comment on attachment 8973879 [details] Bug 1459714 - Use a single transaction for all things associated with a new display list. https://reviewboard.mozilla.org/r/242242/#review248138

Pushed by kgupta@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/af3758713a44 Make WebRenderBridgeParent::ProcessWebRenderParentCommands callers provide the transaction. r=sotaro https://hg.mozilla.org/integration/autoland/rev/7b3c982608df Use a single transaction for all things associated with a new display list. r=sotaro

https://hg.mozilla.org/mozilla-central/rev/af3758713a44 https://hg.mozilla.org/mozilla-central/rev/7b3c982608df