When running MediaStream*Video* tests locally, the following tests crash:
MediaStreamRemoteVideoSourceTest.StartTrack 
MediaStreamVideoSourceTest.AddTrackAndStartSource 
MediaStreamVideoWebRtcSinkTest.NoiseReductionDefaultsToNotSet


The tests don't crash if run individually, but I can easily make them crash if I run them concurrently with other tests.


The crashes look related to TaskSchedulers.
Some output samples:

2 tests crashed:
    MediaStreamRemoteVideoSourceTest.StartTrack (../../content/renderer/media/webrtc/media_stream_remote_video_source_unittest.cc:157)
    MediaStreamVideoSourceTest.AddTrackAndStartSource (../../content/renderer/media/media_stream_video_source_unittest.cc:266)
Tests took 22 seconds.


[ RUN      ] MediaStreamRemoteVideoSourceTest.StartTrack
[14597:14597:0801/153107.447896:2781330430809:FATAL:scoped_task_environment.cc(93)] Check failed: !TaskScheduler::GetInstance(). 
#0 0x7f9cf04b1ff7 base::debug::StackTrace::StackTrace()
#1 0x7f9cf04d9011 logging::LogMessage::~LogMessage()
#2 0x000001746bbb base::test::ScopedTaskEnvironment::ScopedTaskEnvironment()
#3 0x000001588a2c content::MediaStreamRemoteVideoSourceTest::MediaStreamRemoteVideoSourceTest()
#4 0x0000015889e6 testing::internal::TestFactoryImpl<>::CreateTest()
#5 0x00000164d5f8 testing::TestInfo::Run()
#6 0x00000164db47 testing::TestCase::Run()
#7 0x000001653fb7 testing::internal::UnitTestImpl::RunAllTests()
#8 0x000001653c43 testing::UnitTest::Run()
#9 0x00000174c5f4 base::TestSuite::Run()
#10 0x00000175366a base::(anonymous namespace)::LaunchUnitTestsInternal()
#11 0x00000175352a base::LaunchUnitTests()
#12 0x0000013e9206 main
#13 0x7f9ce880cf45 __libc_start_main
#14 0x000000633e57 <unknown>

[ RUN      ] MediaStreamVideoSourceTest.AddTrackAndStartSource
[15068:15068:0801/153329.426461:2781472409373:FATAL:scoped_task_environment.cc(93)] Check failed: !TaskScheduler::GetInstance(). 
#0 0x7f8fb9024ff7 base::debug::StackTrace::StackTrace()
#1 0x7f8fb904c011 logging::LogMessage::~LogMessage()
#2 0x000001746bbb base::test::ScopedTaskEnvironment::ScopedTaskEnvironment()
#3 0x00000151d4e7 content::MediaStreamVideoSourceTest::MediaStreamVideoSourceTest()
#4 0x00000151d486 testing::internal::TestFactoryImpl<>::CreateTest()
#5 0x00000164d5f8 testing::TestInfo::Run()
#6 0x00000164db47 testing::TestCase::Run()
#7 0x000001653fb7 testing::internal::UnitTestImpl::RunAllTests()
#8 0x000001653c43 testing::UnitTest::Run()
#9 0x00000174c5f4 base::TestSuite::Run()
#10 0x00000175366a base::(anonymous namespace)::LaunchUnitTestsInternal()
#11 0x00000175352a base::LaunchUnitTests()
#12 0x0000013e9206 main
#13 0x7f8fb137ff45 __libc_start_main
#14 0x000000633e57 <unknown>

MediaStreamVideoWebRtcSinkTest.NoiseReductionDefaultsToNotSet
[15426:15426:0801/153558.389704:2781621372652:FATAL:scoped_task_environment.cc(93)] Check failed: !TaskScheduler::GetInstance(). 
#0 0x7fbcf9f48ff7 base::debug::StackTrace::StackTrace()
#1 0x7fbcf9f70011 logging::LogMessage::~LogMessage()
#2 0x000001746bbb base::test::ScopedTaskEnvironment::ScopedTaskEnvironment()
#3 0x00000159d58a content::(anonymous namespace)::MediaStreamVideoWebRtcSinkTest::MediaStreamVideoWebRtcSinkTest()
#4 0x00000159d526 testing::internal::TestFactoryImpl<>::CreateTest()
#5 0x00000164d5f8 testing::TestInfo::Run()
#6 0x00000164db47 testing::TestCase::Run()
#7 0x000001653fb7 testing::internal::UnitTestImpl::RunAllTests()
#8 0x000001653c43 testing::UnitTest::Run()
#9 0x00000174c5f4 base::TestSuite::Run()
#10 0x00000175366a base::(anonymous namespace)::LaunchUnitTestsInternal()
#11 0x00000175352a base::LaunchUnitTests()
#12 0x0000013e9206 main
#13 0x7fbcf22a3f45 __libc_start_main
#14 0x000000633e57 <unknown>