I'm suspecting r540846 as a likely culprit, mlippautz@ do you mind taking a look? Feel free to re-assign if you think this is unrelated to your change.

Thanks for triaging, could indeed be my change.

Thanks for looking into this, I'll remove the Sheriff label for now.

Checked the error message and it is indeed my change. Since it is reverted (and was the breaked is in an area related to a debugging feature) I think we are good.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/07861913980abceb9a2b3a988e4d39976599de11

commit 07861913980abceb9a2b3a988e4d39976599de11
Author: Michael Lippautz <mlippautz@chromium.org>
Date: Wed Mar 07 01:33:08 2018

Reland "[wrapper-tracing] Only return trace descriptor for wrapper tracing"

Similar to Oilpan, only return a struct of callbacks and don't actually call
further into visitors.

This reverts commit 559a8e6a64e21c159f53a9755b024cf645eb4d22.

Change-Id: I430c72fd4bee22e7a9f49404f7d461076c613350
Bug:  chromium:802273 ,  chromium:819134 
Reviewed-on: https://chromium-review.googlesource.com/950904
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541267}
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableMarkingVisitorTest.cpp
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/bindings/core/v8/V8EmbedderGraphBuilder.cpp
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/bindings/core/v8/V8EmbedderGraphBuilder.h
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/platform/bindings/ScriptWrappableMarkingVisitor.cpp
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/platform/bindings/ScriptWrappableMarkingVisitor.h
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/platform/bindings/ScriptWrappableVisitor.h
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/platform/bindings/ScriptWrappableVisitorVerifier.h
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/platform/heap/BlinkGC.h
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/platform/heap/GarbageCollected.h
[modify] https://crrev.com/07861913980abceb9a2b3a988e4d39976599de11/third_party/WebKit/Source/platform/heap/TraceTraits.h