This times out pretty frequently without a useful information. I am going to disable the test.

[ RUN      ] MediaRouterUIBrowserTest.OpenDialogFromAppMenu
[66533:3075:0603/233435.848505:WARNING:notification_platform_bridge_mac.mm(510)] AlertNotificationService: XPC connection invalidated.
2018-06-03 23:34:35.937 browser_tests[66533:963224] *** Owner supplied to -[NSTrackingArea initWithRect:options:owner:userInfo:] referenced a deallocating object. Tracking area behavior is undefined. Break on NSTrackingAreaDeallocatingOwnerError to debug.
[66538:775:0603/233435.961968:WARNING:vt_video_decode_accelerator_mac.cc(193)] Failed to create VTDecompressionSession: Error Domain=NSOSStatusErrorDomain Code=-8973 "codecOpenErr" (-8973)
[66538:775:0603/233435.962298:WARNING:vt_video_decode_accelerator_mac.cc(215)] Hardware decoding with VideoToolbox is not supported
[66538:775:0603/233435.987205:ERROR:vt_video_encode_accelerator_mac.cc(516)]  VTCompressionSessionCreate failed: -12908
[66533:775:0603/233436.216815:WARNING:gaia_auth_fetcher.cc(902)] Could not reach Google Accounts servers: errno -11
[66533:86019:0603/233436.365453:ERROR:process_mac.cc(70)] task_policy_set TASK_CATEGORY_POLICY: (ipc/send) invalid destination port (0x10000003)
BrowserTestBase received signal: Terminated: 15. Backtrace:
0   browser_tests                       0x0000000104cb95dc base::debug::StackTrace::StackTrace(unsigned long) + 28
1   browser_tests                       0x00000001054801b5 content::(anonymous namespace)::DumpStackTraceSignalHandler(int) + 229
2   libsystem_platform.dylib            0x00007fff6a215f5a _sigtramp + 26
3   ???                                 0x0000000000000000 0x0 + 0
4   CoreFoundation                      0x00007fff425dbdc5 __CFRunLoopServiceMachPort + 341
5   CoreFoundation                      0x00007fff425db117 __CFRunLoopRun + 1783
6   CoreFoundation                      0x00007fff425da787 CFRunLoopRunSpecific + 487
7   Foundation                          0x00007fff446c6c16 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 277
8   browser_tests                       0x0000000104bfde1e base::MessagePumpNSRunLoop::DoRun(base::MessagePump::Delegate*) + 142
9   browser_tests                       0x0000000104bfc8de base::MessagePumpCFRunLoopBase::Run(base::MessagePump::Delegate*) + 110
10  browser_tests                       0x000000010b606570 chrome::testing::NSRunLoopRunAllPending() + 112
11  browser_tests                       0x0000000104bb2c4d (anonymous namespace)::AppMenuTestApiCocoa::ExecuteCommand(int) + 173
12  browser_tests                       0x000000010148ec0d media_router::MediaRouterUIBrowserTest::TestOpenDialogFromAppMenu() + 829
13  browser_tests                       0x000000010547fe8f content::BrowserTestBase::ProxyRunTestOnMainThreadLoop() + 591
14  browser_tests                       0x0000000104dbbd26 ChromeBrowserMainParts::PreMainMessageLoopRunImpl() + 4726
15  browser_tests                       0x0000000104dba9ae ChromeBrowserMainParts::PreMainMessageLoopRun() + 62
16  browser_tests                       0x0000000102b4ca53 content::BrowserMainLoop::PreMainMessageLoopRun() + 67
17  browser_tests                       0x00000001030c6f85 content::StartupTaskRunner::RunAllTasksNow() + 117
18  browser_tests                       0x0000000102b4b1e2 content::BrowserMainLoop::CreateStartupTasks() + 914
19  browser_tests                       0x0000000102b4f6a5 content::BrowserMainRunnerImpl::Initialize(content::MainFunctionParams const&, std::__1::unique_ptr<content::BrowserProcessSubThread, std::__1::default_delete<content::BrowserProcessSubThread> >) + 101
20  browser_tests                       0x0000000102b48fe5 content::BrowserMain(content::MainFunctionParams const&, std::__1::unique_ptr<content::BrowserProcessSubThread, std::__1::default_delete<content::BrowserProcessSubThread> >) + 229
21  browser_tests                       0x0000000104a497e3 content::RunBrowserProcessMain(content::MainFunctionParams const&, content::ContentMainDelegate*, std::__1::unique_ptr<content::BrowserProcessSubThread, std::__1::default_delete<content::BrowserProcessSubThread> >) + 195
22  browser_tests                       0x0000000104a4a8ee content::ContentMainRunnerImpl::Run() + 686
23  browser_tests                       0x0000000107351067 service_manager::Main(service_manager::MainParams const&) + 2855
24  browser_tests                       0x0000000104a496f4 content::ContentMain(content::ContentMainParams const&) + 68
25  browser_tests                       0x000000010547fa1c content::BrowserTestBase::SetUp() + 3212
26  browser_tests                       0x0000000104d0f895 InProcessBrowserTest::SetUp() + 613
27  browser_tests                       0x000000010193699d testing::Test::Run() + 109
28  browser_tests                       0x00000001019376b0 testing::TestInfo::Run() + 320
29  browser_tests                       0x0000000101937ce7 testing::TestCase::Run() + 279
30  browser_tests                       0x0000000101944477 testing::internal::UnitTestImpl::RunAllTests() + 871
31  browser_tests                       0x00000001019440ed testing::UnitTest::Run() + 109
32  browser_tests                       0x0000000104d33776 base::TestSuite::Run() + 166
33  browser_tests                       0x0000000104ba91a5 ChromeTestSuiteRunner::RunTestSuite(int, char**) + 37
34  browser_tests                       0x00000001054b7b66 content::LaunchTests(content::TestLauncherDelegate*, unsigned long, int, char**) + 470
35  browser_tests                       0x0000000104ba96bb LaunchChromeTests(unsigned long, content::TestLauncherDelegate*, int, char**) + 347
36  browser_tests                       0x0000000104ba90fe main + 94
37  libdyld.dylib                       0x00007fff69f94115 start + 1
38  ???                                 0x000000000000000a 0x0 + 10

Assigning to takumif@ who has done quite some work in chrome/browser/ui/views/media_router recently. Suspecting that one of the CLs cause the increase in timeouts.

CL to disable the test is in the commit queue. This can be taken out of the sheriff queue once landed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/94e1f86276abdcf9fb04ca8cf72ea3440c2c6b9d

commit 94e1f86276abdcf9fb04ca8cf72ea3440c2c6b9d
Author: Dominic Battre <battre@chromium.org>
Date: Mon Jun 04 08:57:17 2018

Disable MediaRouterUIBrowserTest.OpenDialogFromAppMenu on Mac

Disable the test on macOS due to a recent increase in timeouts.

TBR=takumif@chromium.org

Bug:  849146 
Change-Id: I109689361a727a3441796fab15d9ff6a444c1d1a
Reviewed-on: https://chromium-review.googlesource.com/1084480
Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Dominic Battré <battre@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564029}
[modify] https://crrev.com/94e1f86276abdcf9fb04ca8cf72ea3440c2c6b9d/chrome/browser/ui/views/media_router/media_router_ui_browsertest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7eed462400adc7478d33776190104ad595879905

commit 7eed462400adc7478d33776190104ad595879905
Author: Peter Kasting <pkasting@chromium.org>
Date: Wed Jan 02 20:42:46 2019

Re-enable disabled tests in chrome/browser/ui/views/media_router/.

These pass on Windows.

This requires (mostly) reverting
https://chromium-review.googlesource.com/c/chromium/src/+/1005103 .
The revert is not perfect since many things changed since that CL
initially landed (e.g. various tests got disabled).

Bug:  658005 , 678472, 817408,  828031 ,  843599 ,  849146 ,  863945 
Change-Id: I23a3010be1faf962e0a2dfbaaa4a57a3e2cc89d3
Reviewed-on: https://chromium-review.googlesource.com/c/1351874
Reviewed-by: Ben Wells <benwells@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619483}
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/apps/platform_apps/app_window_interactive_uitest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/devtools/devtools_sanity_interactive_browsertest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/extensions/api/tabs/tabs_test.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/notifications/notification_interactive_uitest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/ui/exclusive_access/fullscreen_controller_test.h
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/ui/keyboard_lock_interactive_browsertest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/ui/views/media_router/cast_dialog_view_unittest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/ui/views/media_router/media_router_ui_browsertest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/browser/ui/views/media_router/presentation_receiver_window_view_browsertest.cc
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/chrome/test/base/in_process_browser_test.h
[modify] https://crrev.com/7eed462400adc7478d33776190104ad595879905/testing/buildbot/filters/mac_window_server_killers.browser_tests.filter