suspected cl might be:

https://chromium.googlesource.com/chromium/src//+/ba7d116f43912adfee56093f9b9389196d0503fd
haraken@ could you please look into this.if possible feel free to re- assign .thanks in advance

jbroman@ Can you take this?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/414c42a0b400f213b58314c1b26926f9b897ac8a

commit 414c42a0b400f213b58314c1b26926f9b897ac8a
Author: jbroman <jbroman@chromium.org>
Date: Tue Aug 09 19:37:08 2016

Fix a data race in WebMessagePortChannelImpl.

It's unsafe to pass a WebString (which is logically a RefPtr<StringImpl>)
across threads because the underlying object is not thread-safe ref-counted.
Instead, the base::string16 that the receiving method accepts should be
constructed before posting the task.

BUG= 635659 

Review-Url: https://codereview.chromium.org/2224393002
Cr-Commit-Position: refs/heads/master@{#410761}

[modify] https://crrev.com/414c42a0b400f213b58314c1b26926f9b897ac8a/content/child/webmessageportchannel_impl.cc

ClusterFuzz has detected this issue as fixed in range 410621:410634.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=6517539826040832

Fuzzer: inferno_layout_test_unmodified
Job Type: linux_tsan_chrome_mp
Platform Id: linux

Crash Type: Data race WRITE 8
Crash Address: 0x7d1000056928
Crash State:
  blink::SerializedScriptValue::~SerializedScriptValue
  blink::SerializedScriptValue::~SerializedScriptValue
  blink::MessagePortV8Internal::postMessageImpl
  
Regressed: https://cluster-fuzz.appspot.com/revisions?job=linux_tsan_chrome_mp&range=410296:410304
Fixed: https://cluster-fuzz.appspot.com/revisions?job=linux_tsan_chrome_mp&range=410621:410634

Minimized Testcase (0.77 Kb): https://cluster-fuzz.appspot.com/download/AMIfv96Yvk2sfjHDnuhNn1jUzgQesxB-4ErjPuFLyPIUBneWtXI2GjsRG7trPrBrkGTMMeS7KxyieD7ogI2jNRdKe63ESYzOsQuURJNk7e1WkPbk5H8gHN73bK_l5SD3NzDHDimFe34GmuWGLORz1sDxBWpkvKbCCg?testcase_id=6517539826040832

See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

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