Fix DebugDataSender::mList is accessable in both main and compositor thread.

Hi Dan, Please help to review this change. When TingYu using LayerScope on debugging display list, he met an assertion on debug build. I found another thread-safe problem, which existed for a long time, in layerscope while addressing the root cause of that assertion.

CJ, your patch works for me. I no longer hit the assert in layerscope anymore.

Comment on attachment 8650396 [details] [diff] [review] DebugDataSender thread safe Review of attachment 8650396 [details] [diff] [review]: ----------------------------------------------------------------- Sorry for the delayed review. LGTM with fixing the nits. ::: gfx/layers/LayerScope.cpp @@ +126,5 @@ > + // TBD: RemoveConnection is executed on the compositor thread and > + // AddConntection is executed on the main thread, which might be > + // a problem if a user disconnect and connect readlly quickly at > + // viewer side. > + // We should dispatch RemoveConnection onto main thead. // TBD: RemoveConnection is executed on the compositor thread and // AddConnection is executed on the main thread, which might be // a problem if a user disconnect and connect really quickly on // viewer side. // We should dispatch RemoveConnection from main thread. @@ +752,2 @@ > > + friend class AppenTask; AppendTask? If code compiles with this typo, then the friend declaration isn't required. @@ +772,5 @@ > > + DebugGLData *mData; > + // Keep a strong reference to DebugDataSender to prevent we try to > + // access mHost on mThread, while it's been destroyed on the main > + // thread. // Keep a strong reference to DebugDataSender to prevent UAF // access mHost on mThread, when it's been destroyed on the main // thread.

Try result https://treeherder.mozilla.org/#/jobs?repo=try&revision=09af17bc959f

https://hg.mozilla.org/mozilla-central/rev/3e0ba8a66ed4 https://hg.mozilla.org/mozilla-central/rev/793916ec6dd4