weili@, since this issue is similar to  issue 875707 , could you take look?

I took a quick look. This is not similar to 875707 except they are both on Mac and related to fullscreen. This test is only enabled on Mac so far, and it failed inside CoreFoundation on a particular Mac version. Will leave to people more familiar with Mac.

  [ RUN      ] FullscreenControllerInteractiveTest.MouseLockSilentAfterTargetUnlock
  [3114:3587:1011/044518.749363:WARNING:notification_platform_bridge_mac.mm(512)] AlertNotificationService: XPC connection invalidated.
  [3114:775:1011/044518.942140:ERROR:delegated_frame_host.cc(174)] Not implemented reached in void content::DelegatedFrameHost::SetNeedsBeginFrames(bool)
  [3114:775:1011/044518.954076:ERROR:web_contents_view_mac.mm(487)] Failed to look up NSViewBridgeFactoryHost!
  [3114:775:1011/044519.632484:INFO:CONSOLE(31)] "lockMouse1()", source: http://127.0.0.1:49560/fullscreen_mouselock/fullscreen_mouselock.html (31)
  [3114:775:1011/044519.652101:INFO:CONSOLE(106)] "unlockMouse()", source: http://127.0.0.1:49560/fullscreen_mouselock/fullscreen_mouselock.html (106)
  [3114:775:1011/044519.684011:INFO:CONSOLE(31)] "lockMouse1()", source: http://127.0.0.1:49560/fullscreen_mouselock/fullscreen_mouselock.html (31)
  [3114:775:1011/044519.727381:INFO:CONSOLE(35)] "lock failed", source: http://127.0.0.1:49560/fullscreen_mouselock/fullscreen_mouselock.html (35)
  [3114:775:1011/044519.729462:INFO:CONSOLE(35)] "lock failed", source: http://127.0.0.1:49560/fullscreen_mouselock/fullscreen_mouselock.html (35)
  [3114:775:1011/044519.729531:INFO:CONSOLE(35)] "lock failed", source: http://127.0.0.1:49560/fullscreen_mouselock/fullscreen_mouselock.html (35)
  [3114:82691:1011/044519.729677:WARNING:embedded_test_server.cc(239)] Request not handled. Returning 404: /favicon.ico
  BrowserTestBase received signal: Terminated: 15. Backtrace:
  0   interactive_ui_tests                0x000000011110953f base::debug::StackTrace::StackTrace(unsigned long) + 31
  1   interactive_ui_tests                0x000000011096aaa5 content::(anonymous namespace)::DumpStackTraceSignalHandler(int) + 229
  2   libsystem_platform.dylib            0x00007fffa25e7b3a _sigtramp + 26
  3   ???                                 0x00007fb147574b38 0x0 + 140399382842168
  4   CoreFoundation                      0x00007fff8cc50434 __CFRunLoopServiceMachPort + 212
  5   CoreFoundation                      0x00007fff8cc4f8c1 __CFRunLoopRun + 1361
  6   CoreFoundation                      0x00007fff8cc4f114 CFRunLoopRunSpecific + 420
  7   HIToolbox                           0x00007fff8c1afebc RunCurrentEventLoopInMode + 240
  8   HIToolbox                           0x00007fff8c1afcf1 ReceiveNextEventCommon + 432
  9   HIToolbox                           0x00007fff8c1afb26 _BlockUntilNextEventMatchingListInModeWithFilter + 71
  10  AppKit                              0x00007fff8a748a54 _DPSNextEvent + 1120
  11  AppKit                              0x00007fff8aec47ee -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 2796
  12  interactive_ui_tests                0x000000011036a1b0 __71-[BrowserCrApplication nextEventMatchingMask:untilDate:inMode:dequeue:]_block_invoke + 64
  13  interactive_ui_tests                0x0000000111046f4a base::mac::CallWithEHFrame(void () block_pointer) + 10
  14  interactive_ui_tests                0x000000011036a0e4 -[BrowserCrApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 164
  15  AppKit                              0x00007fff8a73d3db -[NSApplication run] + 926
  16  interactive_ui_tests                0x00000001110591cc base::MessagePumpNSApplication::DoRun(base::MessagePump::Delegate*) + 364
  17  interactive_ui_tests                0x00000001110578ae base::MessagePumpCFRunLoopBase::Run(base::MessagePump::Delegate*) + 110
  18  interactive_ui_tests                0x0000000111083325 base::RunLoop::Run() + 53
  19  interactive_ui_tests                0x000000011098587f content::WindowedNotificationObserver::Wait() + 31
  20  interactive_ui_tests                0x000000010d76f928 ui_test_utils::SendKeyPressAndWait(Browser const*, ui::KeyboardCode, bool, bool, bool, bool, int, content::NotificationSource const&) + 120
  21  interactive_ui_tests                0x000000010d7087e6 FullscreenControllerInteractiveTest_MouseLockSilentAfterTargetUnlock_Test::RunTestOnMainThread() + 1494
  22  interactive_ui_tests                0x0000000110969f5b content::BrowserTestBase::ProxyRunTestOnMainThreadLoop() + 491
  23  interactive_ui_tests                0x000000011036ff60 ChromeBrowserMainParts::PreMainMessageLoopRunImpl() + 4464
  24  interactive_ui_tests                0x000000011036ecf7 ChromeBrowserMainParts::PreMainMessageLoopRun() + 55
  25  interactive_ui_tests                0x000000010e8d56a7 content::BrowserMainLoop::PreMainMessageLoopRun() + 55
  26  interactive_ui_tests                0x000000010ed39627 content::StartupTaskRunner::RunAllTasksNow() + 39
  27  interactive_ui_tests                0x000000010e8d4151 content::BrowserMainLoop::CreateStartupTasks() + 689
  28  interactive_ui_tests                0x000000010e8d7c1c content::BrowserMainRunnerImpl::Initialize(content::MainFunctionParams const&) + 92
  29  interactive_ui_tests                0x000000010e8d2214 content::BrowserMain(content::MainFunctionParams const&) + 180
  30  interactive_ui_tests                0x0000000110176f0b content::ContentMainRunnerImpl::Run(bool) + 747
  31  interactive_ui_tests                0x00000001128c4ae1 service_manager::Main(service_manager::MainParams const&) + 2849
  32  interactive_ui_tests                0x0000000110175f24 content::ContentMain(content::ContentMainParams const&) + 68
  33  interactive_ui_tests                0x0000000110969b8b content::BrowserTestBase::SetUp() + 2843
  34  interactive_ui_tests                0x0000000110311901 InProcessBrowserTest::SetUp() + 529
  35  interactive_ui_tests                0x000000010d85e03d testing::Test::Run() + 109
  36  interactive_ui_tests                0x000000010d85ed30 testing::TestInfo::Run() + 288
  37  interactive_ui_tests                0x000000010d85f357 testing::TestCase::Run() + 247
  38  interactive_ui_tests                0x000000010d86c597 testing::internal::UnitTestImpl::RunAllTests() + 855
  39  interactive_ui_tests                0x000000010d86c21d testing::UnitTest::Run() + 109
  40  interactive_ui_tests                0x00000001110146e6 base::TestSuite::Run() + 166
  41  interactive_ui_tests                0x000000010d770923 InteractiveUITestSuiteRunner::RunTestSuite(int, char**) + 51
  42  interactive_ui_tests                0x0000000110980408 content::LaunchTests(content::TestLauncherDelegate*, unsigned long, int, char**) + 552
  43  interactive_ui_tests                0x000000011030822a LaunchChromeTests(unsigned long, content::TestLauncherDelegate*, int, char**) + 490
  44  interactive_ui_tests                0x000000010d77088c main + 92
  45  libdyld.dylib                       0x00007fffa23d8235 start + 1
  46  ???                                 0x000000000000000c 0x0 + 12
  [69/169] FullscreenControllerInteractiveTest.MouseLockSilentAfterTargetUnlock (TIMED OUT)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b25f9c35e63146e1270640f1d4902a781c803463

commit b25f9c35e63146e1270640f1d4902a781c803463
Author: Vasilii Sukhanov <vasilii@chromium.org>
Date: Thu Oct 11 13:32:16 2018

Disable FullscreenControllerInteractiveTest.MouseLockSilentAfterTargetUnlock

TBR=mgiuca@chromium.org

Bug:  876617 
Change-Id: I096bf298978e9853b9e44471244523b97d50fcc1
Reviewed-on: https://chromium-review.googlesource.com/c/1275955
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598740}
[modify] https://crrev.com/b25f9c35e63146e1270640f1d4902a781c803463/chrome/browser/ui/exclusive_access/fullscreen_controller_interactive_browsertest.cc

*** UI Mass Triage ***

The test is disabled, if you feel this issue should still be addressed, feel free to reopen it or to file a new issue.