I hit the following error after a few minutes of running DEBUG build of Chromium (running it under VS debug session).
Since this is related to BackgroundDownloader I think it is triggered based on some timeout rather than any action that I do in the UI.

---------------------------
Fatal error
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[23680:7856:0705/113153.794:FATAL:com_init_util.cc(69)] Check failed: false. 
Backtrace:
	base::debug::StackTrace::StackTrace [0x100AE967+55] (d:\src\chrome\src\base\debug\stack_trace_win.cc:217)
	base::debug::StackTrace::StackTrace [0x100AE601+17] (d:\src\chrome\src\base\debug\stack_trace.cc:199)
	logging::LogMessage::~LogMessage [0x101031AE+94] (d:\src\chrome\src\base\logging.cc:554)
	base::win::AssertComInitialized [0x103A6AE0+144] (d:\src\chrome\src\base\win\com_init_util.cc:70)
	base::win::`anonymous namespace'::HookManager::DCheckedCoCreateInstance [0x103A5F78+8] (d:\src\chrome\src\base\win\com_init_check_hook.cc:248)
	update_client::`anonymous namespace'::GetGit [0x07603509+41] (d:\src\chrome\src\components\update_client\background_downloader_win.cc:138)
	update_client::BackgroundDownloader::BeginDownloadHelper [0x07601AFA+42] (d:\src\chrome\src\components\update_client\background_downloader_win.cc:485)
	update_client::BackgroundDownloader::BeginDownload [0x076019CD+237] (d:\src\chrome\src\components\update_client\background_downloader_win.cc:469)
	base::internal::FunctorTraits<void (__thiscall update_client::BackgroundDownloader::*)(GURL const &),void>::Invoke<update_client::BackgroundDownloader *,GURL const &> [0x075FEB08+24] (d:\src\chrome\src\base\bind_internal.h:210)
	base::internal::InvokeHelper<0,void>::MakeItSo<void (__thiscall update_client::BackgroundDownloader::*const &)(GURL const &),update_client::BackgroundDownloader *,GURL const &> [0x075FED51+49] (d:\src\chrome\src\base\bind_internal.h:275)
	base::internal::Invoker<base::internal::BindState<void (__thiscall update_client::BackgroundDownloader::*)(GURL const &),base::internal::UnretainedWrapper<update_client::BackgroundDownloader>,GURL>,void __cdecl(void)>::RunImpl<void (__thiscall update_clie [0x075FEF4A+90] (d:\src\chrome\src\base\bind_internal.h:351)
	base::internal::Invoker<base::internal::BindState<void (__thiscall update_client::BackgroundDownloader::*)(GURL const &),base::internal::UnretainedWrapper<update_client::BackgroundDownloader>,GURL>,void __cdecl(void)>::Run [0x07604BB4+36] (d:\src\chrome\src\base\bind_internal.h:329)
	base::Callback<void __cdecl(void),0,0>::Run [0x1004B015+53] (d:\src\chrome\src\base\callback.h:91)
	base::debug::TaskAnnotator::RunTask [0x100B59CB+491] (d:\src\chrome\src\base\debug\task_annotator.cc:61)
	base::internal::TaskTracker::PerformRunTask [0x1026A135+1221] (d:\src\chrome\src\base\task_scheduler\task_tracker.cc:335)
	base::internal::TaskTracker::RunNextTask [0x1026A8AC+348] (d:\src\chrome\src\base\task_scheduler\task_tracker.cc:252)
	base::internal::SchedulerWorker::Thread::ThreadMain [0x1025A853+771] (d:\src\chrome\src\base\task_scheduler\scheduler_worker.cc:80)
	base::`anonymous namespace'::ThreadFunc [0x10275EFC+188] (d:\src\chrome\src\base\threading\platform_thread_win.cc:91)
	BaseThreadInitThunk [0x760462C4+36]
	RtlSubscribeWnfStateChangeNotification [0x77880FD9+1081]
	RtlSubscribeWnfStateChangeNotification [0x77880FA4+1028]
	(No symbol) [0x00000000]

robliao@, Could this be related to  Issue 708303 ?