This is having adverse effects on the CQ. Disabling the test. Will release the bug after doing so.

Stack:

[ RUN      ] ExtensionMessageBubbleTest.TestUninstallExtensionAfterBrowserDestroyed
[8398:8398:0503/021935.796260:4077929988:WARNING:pref_notifier_impl.cc(23)] Pref observer found at shutdown.
[8398:8407:0503/021935.818978:4077952705:ERROR:connection.cc(1888)] Quota sqlite error 1802, errno 0: disk I/O error, sql: CREATE TABLE meta(key LONGVARCHAR NOT NULL UNIQUE PRIMARY KEY, value LONGVARCHAR)
[8398:8407:0503/021935.819008:4077952732:FATAL:connection.cc(1903)] disk I/O error
#0 0x00000592ae4c base::debug::StackTrace::StackTrace()
#1 0x0000058a7cfb logging::LogMessage::~LogMessage()
#2 0x0000063d8009 sql::Connection::OnSqliteError()
#3 0x0000063d5429 sql::Connection::Execute()
#4 0x0000063db06c sql::MetaTable::Init()
#5 0x00000750bc3a storage::QuotaDatabase::CreateSchema()
#6 0x00000750b9aa storage::QuotaDatabase::EnsureDatabaseVersion()
#7 0x000007509eb3 storage::QuotaDatabase::LazyOpen()
#8 0x00000750b6d3 storage::QuotaDatabase::IsOriginDatabaseBootstrapped()
#9 0x0000006372e2 base::internal::ReturnAsParamAdapter<>()
#10 0x0000006373bb _ZN4base8internal7InvokerINS0_9BindStateIPFvNS_12OnceCallbackIFbvEEEPbEJS5_S6_EEEFvvEE7RunOnceEPNS0_13BindStateBaseE
#11 0x0000058fb1ea base::(anonymous namespace)::PostTaskAndReplyRelay::RunTaskAndPostReply()
#12 0x0000058fb619 _ZN4base8internal7InvokerINS0_9BindStateIPFvNS_12_GLOBAL__N_121PostTaskAndReplyRelayEEJS4_EEEFvvEE7RunOnceEPNS0_13BindStateBaseE
#13 0x000005894a75 base::debug::TaskAnnotator::RunTask()
#14 0x0000058f23f5 base::internal::TaskTracker::RunOrSkipTask()
#15 0x00000593a5f8 base::internal::TaskTrackerPosix::RunOrSkipTask()
#16 0x000004f32f35 base::test::ScopedTaskEnvironment::TestTaskTracker::RunOrSkipTask()
#17 0x0000058f188f base::internal::TaskTracker::RunAndPopNextTask()
#18 0x000005958dd8 base::internal::SchedulerWorker::ThreadMain()
#19 0x00000593ac9f base::(anonymous namespace)::ThreadFunc()
#20 0x7f8c997d3184 start_thread
#21 0x7f8c9650903d clone

The failure's in a DCHECK, so it doesn't manifest on the CI bot. Surprisingly, it's not showing up in linux-chromeos-dbg on CI, though: https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=unit_tests%20(with%20patch)&tests=ExtensionMessageBubbleTest.TestUninstallExtensionAfterBrowserDestroyed