ChromeOS leveldb crash on signin (with broken user data dir?)

(1) Build chromeos on linux desktop (ToT @ #503187).
(2) Repeatedly run with --login-manager and an existing --user-data-dir.
(3) Some unknown trigger...
(4) Login to an existing user profile.
Expected: Login works as it normally does.
Actual: Crash on login, happens consistently after the unknown trigger... stack below.

I'll keep the broken --user-data-dir around for a bit if anyone is interested in debugging this.

[40232:40256:0921/091431.548505:FATAL:thread_restrictions.cc(77)] Check failed: false. Waiting is not allowed to be used on this thread to prevent jank and deadlock.  If this task is running inside the TaskScheduler, the TaskRunner used to post it needs to have WithBaseSyncPrimitives() in its TaskTraits.
#0 0x7f960f9e9eec base::debug::StackTrace::StackTrace()
#1 0x7f960fa0fa5c logging::LogMessage::~LogMessage()
#2 0x7f960fa8f95d base::ThreadRestrictions::AssertWaitAllowed()
#3 0x7f960fa65f66 base::ConditionVariable::Wait()
#4 0x55ff98e3b158 leveldb::DBImpl::~DBImpl()
#5 0x55ff98e3b49e leveldb::DBImpl::~DBImpl()
#6 0x55ff98e3a960 leveldb_env::DBTracker::TrackedDBImpl::~TrackedDBImpl()
#7 0x55ff98e3a99e leveldb_env::DBTracker::TrackedDBImpl::~TrackedDBImpl()
#8 0x55ff996ba926 drive::internal::ResourceMetadataStorage::UpgradeOldDB()
#9 0x55ff985b3b66 drive::(anonymous namespace)::InitializeMetadata()
#10 0x55ff980aa446 base::internal::ReturnAsParamAdapter<>()
#11 0x55ff980070cb _ZN4base8internal7InvokerINS0_9BindStateIPFvNS_12OnceCallbackIFNSt3__110unique_ptrINS_5ValueENS4_14default_deleteIS6_EEEEvEEEPS9_EJSB_SC_EEEFvvEE7RunOnceEPNS0_13BindStateBaseE
#12 0x7f960fa85399 base::(anonymous namespace)::PostTaskAndReplyRelay::RunTaskAndPostReply()
#13 0x7f960f9ea77f base::debug::TaskAnnotator::RunTask()
#14 0x7f960fa7a9db base::internal::TaskTracker::RunOrSkipTask()
#15 0x7f960fa7b0b2 base::internal::TaskTrackerPosix::RunOrSkipTask()
#16 0x7f960fa7a11a base::internal::TaskTracker::RunNextTask()
#17 0x7f960fa731c7 base::internal::SchedulerWorker::Thread::ThreadMain()
#18 0x7f960fa850cf base::(anonymous namespace)::ThreadFunc()
#19 0x7f960fb60184 start_thread
#20 0x7f9603b86ffd clone