Maybe Fission related. (DOMFissionEnabled=1)

STR:

1. Enable SW-WR: gfx.webrender.software pref = true
2. Load any YouTube video.

RESULT:

Crash report: https://crash-stats.mozilla.org/report/index/ff91e5e4-31f1-4827-a7b5-e1e010200919

Top 10 frames of crashing thread:

0 XUL mozilla::wr::RenderMacIOSurfaceTextureHostOGL::GetSize const gfx/webrender_bindings/RenderMacIOSurfaceTextureHostOGL.cpp:71
1 XUL mozilla::layers::NativeLayerCA::AttachExternalImage gfx/layers/NativeLayerCA.mm:495
2 XUL <webrender_bindings::swgl_bindings::SwCompositor as webrender::composite::Compositor>::attach_external_image gfx/webrender_bindings/src/swgl_bindings.rs:1181
3 XUL webrender::renderer::Renderer::update_native_surfaces gfx/wr/webrender/src/renderer.rs:6036
4 XUL webrender::renderer::Renderer::render_impl gfx/wr/webrender/src/renderer.rs:3609
5 XUL wr_renderer_render gfx/webrender_bindings/src/bindings.rs:617
6 XUL mozilla::wr::RendererOGL::UpdateAndRender gfx/webrender_bindings/RendererOGL.cpp:156
7 XUL mozilla::wr::RenderThread::UpdateAndRender gfx/webrender_bindings/RenderThread.cpp:505
8 XUL mozilla::wr::RenderThread::HandleFrameOneDoc gfx/webrender_bindings/RenderThread.cpp:360
9 XUL mozilla::detail::RunnableMethodImpl<mozilla::wr::RenderThread*, void  xpcom/threads/nsThreadUtils.h:1240

I bisected this regression to this pushlog for bug 1622966:

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=e87bcd8a1f949b155dff0cc0c7cbad7f4fe03f77&tochange=754fccf0e73ac7c30d06a7ce5ac95ca1ea9300d6

When SWGL is enabled, we're letting BufferTextureHost::PushDisplayItems pass true for aUseExternalSurface, which lets WebRender pass that texture directly back to the compositor.

On MacOS though we're not using the SWGL compositor, and we're forwarding on to the native compositor, which doesn't support BufferTextureHost.

We're going to need to either support this (by making NativeLayerCA::AttachExternalImage detect BufferTextureHosts, and upload to an IOSurface), or disable this flag again on Mac.

When using the native RenderCompositor+SWGL on MacOS, we don't support passing buffer textures directly to the compositor.

This interface is never used directly, and the only consumers of the virtual functions are by the derived classes themselves.

Depends on D93179

NativeLayerCA only understands how to extract the IOSurface from a RenderMacIOSurfaceTextureHost.

Rather than trying to support both types, this just merges them, as they are both just an IOSurface pointer and some associated helper functions.

Depends on D93180

https://hg.mozilla.org/mozilla-central/rev/97337b1dc812
https://hg.mozilla.org/mozilla-central/rev/4069bebe3082
https://hg.mozilla.org/mozilla-central/rev/c80e9fd82c9d