Concretely:
SitePerProcessHitTestDataGenerationBrowserTest.PointerEventsNoneOOPIF/2
see 
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-rel
e.g.
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-rel/13046
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-rel/13049
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-rel/13055


[ RUN      ] SitePerProcessHitTestDataGenerationBrowserTest.PointerEventsNoneOOPIF/2
[4566:4639:0907/092530.894711:ERROR:network_service.cc(84)] Not implemented reached in std::unique_ptr<net::NetworkChangeNotifier> network::(anonymous namespace)::CreateNetworkChangeNotifierIfNeeded()
DevTools listening on ws://127.0.0.1:44008/devtools/browser/2f8def88-0fe7-4cf6-a13b-67f00aee7a35
[4566:4566:0907/092530.926132:ERROR:proxy_resolution_service.cc(1556)] ProxyConfigService for ChromeOS should be created in profile_io_data.cc::CreateProxyConfigService and this should be used only for examples.
../../content/browser/site_per_process_hit_test_browsertest.cc:5304: Failure
Expected equality of these values:
  expected_region2.ToString()
    Which is: "0,0 100x100"
  hit_test_data[3].rect.ToString()
    Which is: "0,0 3x0"
Stack trace:
#0 0x0000013cf0ac testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop()
#1 0x0000013cea89 testing::internal::AssertHelper::operator=()
#2 0x000000a99531 content::SitePerProcessHitTestDataGenerationBrowserTest_PointerEventsNoneOOPIF_Test::RunTestOnMainThread()
#3 0x0000024f550b content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#4 0x00000255f058 content::ShellBrowserMainParts::PreMainMessageLoopRun()
#5 0x000001f4ddd1 content::BrowserMainLoop::PreMainMessageLoopRun()
#6 0x0000022c16b7 content::StartupTaskRunner::RunAllTasksNow()
#7 0x000001f4c75d content::BrowserMainLoop::CreateStartupTasks()
#8 0x000001f50263 content::BrowserMainRunnerImpl::Initialize()
#9 0x000002547079 ShellBrowserMain()
#10 0x00000253d67f content::ShellMainDelegate::RunProcess()
#11 0x000001e7f3fd content::ContentMainRunnerImpl::Run()
#12 0x000003b2cfe0 service_manager::Main()
#13 0x0000015fa3e4 content::ContentMain()
#14 0x0000024f513d content::BrowserTestBase::SetUp()
#15 0x0000024eb66f content::ContentBrowserTest::SetUp()
../../content/browser/site_per_process_hit_test_browsertest.cc:5306: Failure
Value of: expected_transform2.ApproximatelyEqual(hit_test_data[3].transform())
  Actual: false
Expected: true
Stack trace:
#0 0x0000013cf0ac testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop()
#1 0x0000013cea89 testing::internal::AssertHelper::operator=()
#2 0x000000a99687 content::SitePerProcessHitTestDataGenerationBrowserTest_PointerEventsNoneOOPIF_Test::RunTestOnMainThread()
#3 0x0000024f550b content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#4 0x00000255f058 content::ShellBrowserMainParts::PreMainMessageLoopRun()
#5 0x000001f4ddd1 content::BrowserMainLoop::PreMainMessageLoopRun()
#6 0x0000022c16b7 content::StartupTaskRunner::RunAllTasksNow()
#7 0x000001f4c75d content::BrowserMainLoop::CreateStartupTasks()
#8 0x000001f50263 content::BrowserMainRunnerImpl::Initialize()
#9 0x000002547079 ShellBrowserMain()
#10 0x00000253d67f content::ShellMainDelegate::RunProcess()
#11 0x000001e7f3fd content::ContentMainRunnerImpl::Run()
#12 0x000003b2cfe0 service_manager::Main()
#13 0x0000015fa3e4 content::ContentMain()
#14 0x0000024f513d content::BrowserTestBase::SetUp()
#15 0x0000024eb66f content::ContentBrowserTest::SetUp()
../../content/browser/site_per_process_hit_test_browsertest.cc:5307: Failure
Expected equality of these values:
  kFastHitTestFlags
    Which is: 53
  hit_test_data[3].flags
    Which is: 0
Stack trace:
#0 0x0000013cf0ac testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop()
#1 0x0000013cea89 testing::internal::AssertHelper::operator=()
#2 0x000000a9979e content::SitePerProcessHitTestDataGenerationBrowserTest_PointerEventsNoneOOPIF_Test::RunTestOnMainThread()
#3 0x0000024f550b content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#4 0x00000255f058 content::ShellBrowserMainParts::PreMainMessageLoopRun()
#5 0x000001f4ddd1 content::BrowserMainLoop::PreMainMessageLoopRun()
#6 0x0000022c16b7 content::StartupTaskRunner::RunAllTasksNow()
#7 0x000001f4c75d content::BrowserMainLoop::CreateStartupTasks()
#8 0x000001f50263 content::BrowserMainRunnerImpl::Initialize()
#9 0x000002547079 ShellBrowserMain()
#10 0x00000253d67f content::ShellMainDelegate::RunProcess()
#11 0x000001e7f3fd content::ContentMainRunnerImpl::Run()
#12 0x000003b2cfe0 service_manager::Main()
#13 0x0000015fa3e4 content::ContentMain()
#14 0x0000024f513d content::BrowserTestBase::SetUp()
#15 0x0000024eb66f content::ContentBrowserTest::SetUp()
[  FAILED  ] SitePerProcessHitTestDataGenerationBrowserTest.PointerEventsNoneOOPIF/2, where GetParam() = (2, 1) (497 ms)


sunxd@ can you take a look and triage plz? Thanks