Narrow bisect:
https://chromium.googlesource.com/chromium/src/+log/5a6f502d0e2ab2c368dbf3564061695931e882c7..20cddbda08c2478e6fde6ec571ccdaa51ac1eb9f?pretty=fuller&n=1000

suspecting:r568705?

Could you please help to reassign if your change is not the cause for this change?

Good build:51.0.2663.0
Bad build:51.0.2664.0

Deleted: actual.mp4 1.4 MB

actual.mp4 1.4 MB Download

Crash ID: 0a9cb00800000000

Stack trace for the Crash ID generated:
=======================================
CRASHED [EXCEPTION_ACCESS_VIOLATION_READ @ 0x00000030 ] MAGIC SIGNATURE THREAD
0x000007fedebfb307	(chrome_child.dll -workerglobalscope.cpp:323 )	blink::WorkerGlobalScope::isJSExecutionForbidden()
0x000007fedf108839	(chrome_child.dll -v8abstracteventlistener.cpp:70 )	blink::V8AbstractEventListener::handleEvent(blink::ExecutionContext *,blink::Event *)
0x000007fede92dbcf	(chrome_child.dll -eventtarget.cpp:448 )	blink::EventTarget::fireEventListeners(blink::Event *,blink::EventTargetData *,blink::HeapVector<blink::RegisteredEventListener,1> &)
0x000007fede92d71d	(chrome_child.dll -eventtarget.cpp:372 )	blink::EventTarget::fireEventListeners(blink::Event *)
0x000007fede92d488	(chrome_child.dll -eventtarget.cpp:285 )	blink::EventTarget::dispatchEventInternal(WTF::RawPtr<blink::Event>)
0x000007fede9b5883	(chrome_child.dll -messageport.cpp:216 )	blink::MessagePort::dispatchMessages()
0x000007fedec2d7f7	(chrome_child.dll -workerthread.cpp:120 )	blink::WorkerThread::performTask(WTF::PassOwnPtr<blink::ExecutionContextTask>,bool)
0x000007fedec2f0cd	(chrome_child.dll -functional.h:232 )	WTF::PartBoundFunctionImpl<std::tuple<blink::WorkerThread * &&,WTF::PassOwnPtr<blink::ExecutionContextTask> &&,bool &&>,WTF::FunctionWrapper<void ( blink::WorkerThread::*)(WTF::PassOwnPtr<blink::ExecutionContextTask>,bool)> >::operator()()
0x000007fee0e25a2e	(chrome_child.dll -web_task_runner_impl.cc:68 )	scheduler::WebTaskRunnerImpl::runTask(scoped_ptr<blink::WebTaskRunner::Task,std::default_delete<blink::WebTaskRunner::Task> >)
0x000007fedfd86271	(chrome_child.dll -bind_internal.h:354 )	base::internal::Invoker<base::IndexSequence<0>,base::internal::BindState<base::internal::RunnableAdapter<void (*)(scoped_ptr<mojo::edk::NodeController,std::default_delete<mojo::edk::NodeController> >)>,void ,base::internal::PassedWrapper<scoped_ptr<mojo::edk::NodeController,std::default_delete<mojo::edk::NodeController> > > >,base::internal::InvokeHelper<0,void,base::internal::RunnableAdapter<void (*)(scoped_ptr<mojo::edk::NodeController,std::default_delete<mojo::edk::NodeController> >)> >,void >::Run(base::internal::BindStateBase *)
0x000007fede678918	(chrome_child.dll -task_annotator.cc:51 )	base::debug::TaskAnnotator::RunTask(char const *,base::PendingTask const &)
0x000007fee0e2ad2e	(chrome_child.dll -task_queue_manager.cc:288 )	scheduler::TaskQueueManager::ProcessTaskFromWorkQueue(scheduler::internal::WorkQueue *,scheduler::internal::TaskQueueImpl::Task *)
0x000007fee0e2a4de	(chrome_child.dll -task_queue_manager.cc:200 )	scheduler::TaskQueueManager::DoWork(base::TimeTicks,bool)
0x000007fee00d2a82	(chrome_child.dll -bind_internal.h:314 )	base::internal::InvokeHelper<1,void,base::internal::RunnableAdapter<void ( content::WebFileWriterBase::*)(__int64,bool)> >::MakeItSo<base::WeakPtr<content::WebFileWriterImpl>,__int64 const &,bool const &>(base::internal::RunnableAdapter<void ( content::WebFileWriterBase::*)(__int64,bool)>,base::WeakPtr<content::WebFileWriterImpl>,__int64 const &,bool const &)
0x000007fee0e2b0e1	(chrome_child.dll -bind_internal.h:354 )	base::internal::Invoker<base::IndexSequence<0,1,2>,base::internal::BindState<base::internal::RunnableAdapter<void ( scheduler::TaskQueueManager::*)(base::TimeTicks,bool)>,void ,base::WeakPtr<scheduler::TaskQueueManager>,base::TimeTicks &,bool>,base::internal::InvokeHelper<1,void,base::internal::RunnableAdapter<void ( scheduler::TaskQueueManager::*)(base::TimeTicks,bool)> >,void >::Run(base::internal::BindStateBase *)
0x000007fede678918	(chrome_child.dll -task_annotator.cc:51 )	base::debug::TaskAnnotator::RunTask(char const *,base::PendingTask const &)
0x000007fede6342fb	(chrome_child.dll -message_loop.cc:476 )	base::MessageLoop::RunTask(base::PendingTask const &)
0x000007fede634e43	(chrome_child.dll -message_loop.cc:597 )	base::MessageLoop::DoWork()
0x000007fede676505	(chrome_child.dll -message_pump_default.cc:33 )	base::MessagePumpDefault::Run(base::MessagePump::Delegate *)
0x000007fede67703e	(chrome_child.dll -run_loop.cc:35 )	base::RunLoop::Run()
0x000007fede656120	(chrome_child.dll -thread.cc:202 )	base::Thread::Run(base::MessageLoop *)
0x000007fede656477	(chrome_child.dll -thread.cc:254 )	base::Thread::ThreadMain()
0x000007fede65fd0c	(chrome_child.dll -platform_thread_win.cc:84 )	base::`anonymous namespace'::ThreadFunc(void *)
0x76e959ec	(kernel32.dll + 0x000159ec )	BaseThreadInitThunk
0x76fcb370	(ntdll.dll + 0x0002b370 )	RtlUserThreadStart

Adding Release block label, please undo if not the case. This issue is observed only on Windows as not seeing it on MAC and Linux.