This test is flaky on try bots. Example log: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8924132342688454928/+/steps/single_process_mash_interactive_ui_tests__with_patch_/0/logs/AppWindowInteractiveTest.TestFullscreen__status_FAILURE_/0

Also failed locally 2 out of 10 times when built with target_os="chromeos" and run with
> interactive_ui_tests --enable-features=SingleProcessMash --gtest_filter=AppWindowInteractiveTest.TestFullscreen

Failed run output:

[ RUN      ] AppWindowInteractiveTest.TestFullscreen
[1:1:0116/155416.100308:INFO:hugepage_text.cc(68)] Mlocking text pages failed: Cannot allocate memory (12)
[21108:21108:0116/155416.225828:WARNING:user_policy_manager_factory_chromeos.cc(208)] No policy loaded for known non-enterprise user
[21108:21108:0116/155416.297969:WARNING:wallpaper_controller_client.cc(358)] Cannot get wallpaper files id in RemovePolicyWallpaper. This should never happen under normal circumstances.
[21108:21108:0116/155416.388487:WARNING:personal_data_manager.cc(487)] 0x52c1c67280 refresh is done, notifying PersonalDataChanged
[21108:21108:0116/155416.389908:WARNING:personal_data_manager.cc(487)] 0x52c1ef7a00 refresh is done, notifying PersonalDataChanged
[21108:21108:0116/155416.417753:ERROR:gpu_interface_provider.cc(87)] Not implemented reached in virtual void content::GpuInterfaceProvider::RegisterOzoneGpuInterfaces(service_manager::BinderRegistry *)
[21108:21108:0116/155416.478057:ERROR:remote_text_input_client.cc(144)] Not implemented reached in virtual void RemoteTextInputClient::OnInputMethodChanged()
[21108:21108:0116/155416.478087:ERROR:remote_text_input_client.cc(101)] Not implemented reached in virtual ui::TextInputClient::FocusReason RemoteTextInputClient::GetFocusReason() const
[21108:21108:0116/155416.478093:ERROR:remote_text_input_client.cc(185)] Not implemented reached in virtual bool RemoteTextInputClient::ShouldDoLearning()
[21108:21108:0116/155416.478126:ERROR:remote_text_input_client.cc(95)] Not implemented reached in virtual bool RemoteTextInputClient::HasCompositionText() const
[21108:21108:0116/155416.478131:ERROR:remote_text_input_client.cc(107)] Not implemented reached in virtual bool RemoteTextInputClient::GetTextRange(gfx::Range *) const
[21108:21108:0116/155416.754558:ERROR:multi_user_window_manager_client_stub.cc(56)] Not implemented reached in virtual void MultiUserWindowManagerClientStub::AddObserver(MultiUserWindowManagerClient::Observer *)
[21108:21108:0116/155416.764607:ERROR:render_widget_host_view_aura.cc(1308)] Not implemented reached in virtual base::i18n::TextDirection content::RenderWidgetHostViewAura::GetTextDirection() const
[21108:21108:0116/155416.826163:INFO:CONSOLE(0)] "[FAIL] createFullscreen: API Test Error in createFullscreen
Actual: 512
Expected: 1280
Error
    at extensions::test:243:18
    at chrome-extension://ihbompniebllhkdogomofnmkjapanpnk/test.js:241:21
    at safeFunctionApply (extensions::test:288:26)
    at extensions::test:313:18
    at extensions::app.window:183:11", source: chrome-extension://ihbompniebllhkdogomofnmkjapanpnk/_generated_background_page.html (0)
[21108:21108:0116/155416.826289:INFO:CONSOLE(291)] "Uncaught chrome.test.failure", source: extensions::test (291)
../../chrome/browser/apps/platform_apps/app_window_interactive_uitest.cc:460: Failure
Value of: RunAppWindowInteractiveTest("testFullscreen")
  Actual: false
Expected: true
Failed 1 of 1 tests
Stack trace:
#0 0x5646f7643cbc testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop()
#1 0x5646f7643609 testing::internal::AssertHelper::operator=()
#2 0x5646f731daa0 AppWindowInteractiveTest_TestFullscreen_Test::RunTestOnMainThread()
#3 0x5646face055a content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#4 0x5646fa7bd426 ChromeBrowserMainParts::PreMainMessageLoopRunImpl()
#5 0x5646fa7bc1f8 ChromeBrowserMainParts::PreMainMessageLoopRun()
#6 0x5646f935f5a0 chromeos::ChromeBrowserMainPartsChromeos::PreMainMessageLoopRun()
#7 0x5646f85842b2 content::BrowserMainLoop::PreMainMessageLoopRun()
#8 0x5646f8a51b35 content::StartupTaskRunner::RunAllTasksNow()
#9 0x5646f8582f95 content::BrowserMainLoop::CreateStartupTasks()
#10 0x5646f85864a4 content::BrowserMainRunnerImpl::Initialize()
#11 0x5646f8580fbc content::BrowserMain()
#12 0x5646fa5966dc content::ContentMainRunnerImpl::RunServiceManager()
#13 0x5646fa5962e1 content::ContentMainRunnerImpl::Run()
#14 0x5646fca375d3 service_manager::Main()
#15 0x5646fa594744 content::ContentMain()
#16 0x5646face0042 content::BrowserTestBase::SetUp()
#17 0x5646fa7ad458 InProcessBrowserTest::SetUp()

[21108:21108:0116/155416.945678:ERROR:multi_user_window_manager_client_stub.cc(60)] Not implemented reached in virtual void MultiUserWindowManagerClientStub::RemoveObserver(MultiUserWindowManagerClient::Observer *)
[21108:21124:0116/155417.084211:WARNING:discardable_shared_memory_manager.cc(410)] Some MojoDiscardableSharedMemoryManagerImpls are still alive. They will be leaked.
[21108:21203:0116/155417.087198:WARNING:internal_linux.cc(64)] Failed to read /proc/21141/stat
[21108:21108:0116/155417.091153:WARNING:pref_notifier_impl.cc(23)] Pref observer found at shutdown.
[21108:21108:0116/155417.091188:WARNING:pref_notifier_impl.cc(23)] Pref observer found at shutdown.
[  FAILED  ] AppWindowInteractiveTest.TestFullscreen, where TypeParam =  and GetParam() =  (1066 ms)