Update : 

Precondition : Freshly install chrome.

Crash ID a50dd616-d0f7-4c7c-8713-e8be1d38c9d5 (Server ID: 087f240880000000)

Deleted: Actual_video.mp4 1.1 MB

	Actual_video.mp4 1.1 MB View Download

Able to reproduce the issue in fresh install due to that unable to run the per revision bisect.So providing the manual bisect using below revisions.

Good build: 57.0.2986.0 (Revision: 444600)
Bad build: 57.0.2987.0 (Revision: 444943)


Stack Trace:
============
Thread 55 CRASHED [EXCEPTION_ACCESS_VIOLATION_EXEC @ 0x00007fff99c14e50 ] MAGIC SIGNATURE THREAD
Stack Quality89%Show frame trust levels
0x00007fff99c14e50	(chrome.dll + 0x02bc4e50 )	
0x00007fff99431157	(chrome.dll -get_updates_processor.cc:194 )	syncer::GetUpdatesProcessor::PrepareGetUpdates(syncer::EnumSet<syncer::ModelType,2,38>,sync_pb::ClientToServerMessage *)
0x00007fff9943080f	(chrome.dll -get_updates_processor.cc:176 )	syncer::GetUpdatesProcessor::DownloadUpdates(syncer::EnumSet<syncer::ModelType,2,38> *,syncer::SyncCycle *,bool)
0x00007fff99417398	(chrome.dll -syncer.cc:112 )	syncer::Syncer::DownloadAndApplyUpdates(syncer::EnumSet<syncer::ModelType,2,38> *,syncer::SyncCycle *,syncer::GetUpdatesProcessor *,bool)
0x00007fff99417309	(chrome.dll -syncer.cc:88 )	syncer::Syncer::ConfigureSyncShare(syncer::EnumSet<syncer::ModelType,2,38>,sync_pb::GetUpdatesCallerInfo_GetUpdatesSource,syncer::SyncCycle *)
0x00007fff994183c2	(chrome.dll -sync_scheduler_impl.cc:490 )	syncer::SyncSchedulerImpl::DoConfigurationSyncCycleJob(syncer::SyncSchedulerImpl::JobPriority)
0x00007fff99419f06	(chrome.dll -sync_scheduler_impl.cc:711 )	syncer::SyncSchedulerImpl::TrySyncCycleJobImpl()
0x00007fff97a5e091	(chrome.dll -bind_internal.h:305 )	base::internal::InvokeHelper<1,void>::MakeItSo<void ( content::RenderWidgetHostImpl::*const &)(void),base::WeakPtr<content::RenderWidgetHostImpl> const &>(void ( content::RenderWidgetHostImpl::*const &)(void),base::WeakPtr<content::RenderWidgetHostImpl> const &)
0x00007fff9713ee02	(chrome.dll -callback.h:68 )	base::internal::RunMixin<base::Callback<void ,0,0> >::Run( ?? )
0x00007fff971530c4	(chrome.dll -task_annotator.cc:52 )	base::debug::TaskAnnotator::RunTask(char const *,base::PendingTask *)
0x00007fff970faec3	(chrome.dll -message_loop.cc:421 )	base::MessageLoop::RunTask(base::PendingTask *)
0x00007fff970fbb04	(chrome.dll -message_loop.cc:523 )	base::MessageLoop::DoWork()
0x00007fff97154418	(chrome.dll -message_pump_default.cc:33 )	base::MessagePumpDefault::Run(base::MessagePump::Delegate *)
0x00007fff9711f8d3	(chrome.dll -run_loop.cc:37 )	base::RunLoop::Run()
0x00007fff970f971d	(chrome.dll -thread.cc:328 )	base::Thread::ThreadMain()
0x00007fff970c4f3f	(chrome.dll -platform_thread_win.cc:84 )	base::`anonymous namespace'::ThreadFunc
0x00007fffc6038101	(KERNEL32.DLL + 0x00018101 )	BaseThreadInitThunk
0x00007fffc706c5b3	(ntdll.dll + 0x0005c5b3 )	RtlUserThreadStart


CHANGE-LOG URL:
----------------
https://chromium.googlesource.com/chromium/src/+log/57.0.2986.0..57.0.2987.0?pretty=fuller&n=10000


From the CL above, assigning the issue to the concern owner

@pavely: 
------------------
Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to concern owner.

Review-Url:  https://codereview.chromium.org/2641523004

Adding RB-Dev to this issue if not required please feel free to remove.

Thank you!

Update: 

Able to reproduce the issue in Ubuntu 14.04 and unable to test the issue in MAC OS as build version #57.0.2987.0 for mac was failed.

Thank You!

Update :
Issue is also reproducible in Mac(10.12.1, 10.11.6, 10.12) on build #57.0.2987.0

Thank You!

Issue 683102 has been merged into this issue.

Crash showing up in Android too.

Bumping priority as this completely breaks signin.

pavely@, Can you please revert the change ASAP?

PS: This is a branching (2987) build and we are waiting for rest of the M57 branching tasks.

Thank you!

The change has been reverted, see https://codereview.chromium.org/2644373003/

I've reverted my change: http://crrev.com/2644373003
Sorry for the inconvenience.

I am seeing it as already reverted (https://codereview.chromium.org/2644373003/). Could you please merge it to 2987 branch?

I'm triggering a new 2987 build now.

I've merged revert to 2987: http://crrev.com/2641253004

Thank you Pavel for all the help.

Users experienced this crash on the following builds:

Win Canary 57.0.2987.0 -  10.42 CPM, 57 reports, 56 clients (signature syncer::GetUpdatesProcessor::PrepareGetUpdates)

If this update was incorrect, please add "Fracas-Wrong" label to prevent future updates.

- Go/Fracas

Users experienced this crash on the following builds:

Win Canary 57.0.2987.0 -  11.52 CPM, 63 reports, 61 clients (signature syncer::`anonymous namespace'::ShouldRequestEncryptionKey)

If this update was incorrect, please add "Fracas-Wrong" label to prevent future updates.

- Go/Fracas

Verified the revert in the latest M-57 branched build(57.0.2987.6) on Windows-10, Mac OS 10.12.2 and Linux Ubuntu 14.04. Browser doesn't crash on signing into chrome. Adding the verified label therefore.

Can we close this out/downgrade priority?

Yes, downgrading to P2.

Why downgrade instead of close out the issue?  Since the crash is fixed, this bug is fixed, right?  Reference the original bug tracking the first landing when re-landing.