First seen: 20190223-492e4409f468

I am unable to reproduce with any of the reported test cases.

Report from m-c: 20190402-ce51e7ec806c

Assertion failure: false (WeakPtr accessed from multiple threads), at src/obj-firefox/dist/include/mozilla/WeakPtr.h:158

#0 AssertSafeToAccessFromNonOwningThread /src/obj-firefox/dist/include/mozilla/WeakPtr.h:158:5
#1 detach /src/obj-firefox/dist/include/mozilla/WeakPtr.h:195
#2 mozilla::SupportsWeakPtr<mozilla::layers::WebRenderBridgeParent>::~SupportsWeakPtr() /src/obj-firefox/dist/include/mozilla/WeakPtr.h:212
#3 mozilla::layers::WebRenderBridgeParent::~WebRenderBridgeParent() /src/gfx/layers/wr/WebRenderBridgeParent.cpp:356:50
#4 ~WebRenderBridgeParent /src/gfx/layers/wr/WebRenderBridgeParent.cpp:356:49
#5 non-virtual thunk to mozilla::layers::WebRenderBridgeParent::~WebRenderBridgeParent() /src/gfx/layers/wr/WebRenderBridgeParent.cpp
#6 Release /src/obj-firefox/dist/include/mozilla/layers/ISurfaceAllocator.h:71:3
#7 Release /src/obj-firefox/dist/include/mozilla/RefPtr.h:46
#8 Release /src/obj-firefox/dist/include/mozilla/RefPtr.h:363
#9 ~RefPtr /src/obj-firefox/dist/include/mozilla/RefPtr.h:77
#10 ~ScheduleSharedSurfaceRelease /src/gfx/layers/wr/WebRenderBridgeParent.cpp:247
#11 mozilla::layers::WebRenderBridgeParent::ScheduleSharedSurfaceRelease::~ScheduleSharedSurfaceRelease() /src/gfx/layers/wr/WebRenderBridgeParent.cpp:247
#12 webrender_api::api::NotificationRequest::notify::h8557687ac67e8174 /src/gfx/wr/webrender_api/src/api.rs:1498:12
#13 webrender::renderer::Renderer::update_texture_cache::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h6325ad4b26720eff /src/gfx/wr/webrender/src/renderer.rs:3384
#14 webrender::util::drain_filter::hf7fc7a4b5492b51c /src/gfx/wr/webrender/src/util.rs:933
#15 webrender::renderer::Renderer::update_texture_cache::_$u7b$$u7b$closure$u7d$$u7d$::h0fc333f68a11cb43 /src/gfx/wr/webrender/src/renderer.rs:3381
#16 webrender::profiler::TimeProfileCounter::profile::hbd290cfa27b5854c /src/gfx/wr/webrender/src/profiler.rs:282
#17 webrender::renderer::Renderer::update_texture_cache::hff5c0fc7f2aec8e9 /src/gfx/wr/webrender/src/renderer.rs:3260
#18 webrender::renderer::Renderer::render_impl::_$u7b$$u7b$closure$u7d$$u7d$::h45856fdc73ea06f7 /src/gfx/wr/webrender/src/renderer.rs:2997:12
#19 webrender::profiler::TimeProfileCounter::profile::h71c8d968d3fe668a /src/gfx/wr/webrender/src/profiler.rs:282
#20 webrender::renderer::Renderer::render_impl::h3e4c3aab02a5f77c /src/gfx/wr/webrender/src/renderer.rs:2987
#21 webrender::renderer::Renderer::render::he7b96931ffd41865 /src/gfx/wr/webrender/src/renderer.rs:2927:21
#22 wr_renderer_render /src/gfx/webrender_bindings/src/bindings.rs:652
#23 mozilla::wr::RendererOGL::UpdateAndRender(mozilla::Maybe<mozilla::gfx::IntSizeTyped<mozilla::gfx::UnknownUnits> > const&, mozilla::Maybe<mozilla::Range<unsigned char> > const&, bool, mozilla::wr::RendererStats*) /src/gfx/webrender_bindings/RendererOGL.cpp:121:8
#24 mozilla::wr::RenderThread::UpdateAndRender(mozilla::wr::WrWindowId, mozilla::layers::BaseTransactionId<mozilla::VsyncIdType> const&, mozilla::TimeStamp const&, bool, mozilla::Maybe<mozilla::gfx::IntSizeTyped<mozilla::gfx::UnknownUnits> > const&, mozilla::Maybe<mozilla::Range<unsigned char> > const&, bool) /src/gfx/webrender_bindings/RenderThread.cpp:373:26
#25 mozilla::wr::RenderThread::HandleFrame(mozilla::wr::WrWindowId, bool) /src/gfx/webrender_bindings/RenderThread.cpp:266:3
#26 applyImpl<mozilla::wr::RenderThread, void (mozilla::wr::RenderThread::*)(mozilla::wr::WrWindowId, bool), StoreCopyPassByConstLRef<mozilla::wr::WrWindowId>, StoreCopyPassByConstLRef<bool> , 0, 1> /src/obj-firefox/dist/include/nsThreadUtils.h:1122:12
#27 apply<mozilla::wr::RenderThread, void (mozilla::wr::RenderThread::*)(mozilla::wr::WrWindowId, bool)> /src/obj-firefox/dist/include/nsThreadUtils.h:1128
#28 mozilla::detail::RunnableMethodImpl<mozilla::wr::RenderThread*, void (mozilla::wr::RenderThread::*)(mozilla::wr::WrWindowId, bool), true, (mozilla::RunnableKind)0, mozilla::wr::WrWindowId, bool>::Run() /src/obj-firefox/dist/include/nsThreadUtils.h:1174
#29 RunTask /src/ipc/chromium/src/base/message_loop.cc:442:9
#30 MessageLoop::DeferOrRunPendingTask(MessageLoop::PendingTask&&) /src/ipc/chromium/src/base/message_loop.cc:450
#31 MessageLoop::DoWork() /src/ipc/chromium/src/base/message_loop.cc:523:13
#32 base::MessagePumpDefault::Run(base::MessagePump::Delegate*) /src/ipc/chromium/src/base/message_pump_default.cc:35:31
#33 RunInternal /src/ipc/chromium/src/base/message_loop.cc:315:10
#34 RunHandler /src/ipc/chromium/src/base/message_loop.cc:308
#35 MessageLoop::Run() /src/ipc/chromium/src/base/message_loop.cc:290
#36 base::Thread::ThreadMain() /src/ipc/chromium/src/base/thread.cc:192:16
#37 ThreadFunc(void*) /src/ipc/chromium/src/base/platform_thread_posix.cc:40:13

This was last reported by fuzzers running m-c 20200723-38eb7e998859.