In https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/fuchsia-fyi-arm64-rel/782 this flaked, and try-flakes shows it flaking in try runs on Fuchsia/x64 (e.g. https://ci.chromium.org/p/chromium/builders/luci.chromium.try/fuchsia_x64/79651), with:

[ RUN      ] WebContentsAudioInputStreamTest.MirroringNothingWithTargetChange/1
../../content/browser/media/capture/web_contents_audio_input_stream_unittest.cc:352: Failure
Mock function called more times than expected - returning directly.
    Function call: StartMirroring(0x86a444818820)
         Expected: to be called once
           Actual: called twice - over-saturated and active
Stack trace:
#00: testing::internal::AssertHelper::operator=(testing::Message const&) const at gtest.cc:?
#01: testing::internal::GoogleTestFailureReporter::ReportFailure(testing::internal::FailureReporterInterface::FailureType, char const*, int, std::__2::basic_string<char, std::__2::char_traits<char>, std::__2::allocator<char> > const&) at gmock-internal-utils.cc:?
#02: testing::internal::UntypedFunctionMockerBase::UntypedInvokeWith(void*) at gmock-spec-builders.cc:?
#03: content::(anonymous namespace)::MockAudioMirroringManager::StartMirroring(content::AudioMirroringManager::MirroringDestination*) at web_contents_audio_input_stream_unittest.cc:?

../../content/browser/media/capture/web_contents_audio_input_stream_unittest.cc:243: Failure
Actual function call count doesn't match EXPECT_CALL(*mock_mirroring_manager_, StartMirroring(NotNull()))...
         Expected: to be called once
           Actual: never called - unsatisfied and active
Stack trace:
#00: testing::internal::AssertHelper::operator=(testing::Message const&) const at gtest.cc:?
#01: testing::internal::GoogleTestFailureReporter::ReportFailure(testing::internal::FailureReporterInterface::FailureType, char const*, int, std::__2::basic_string<char, std::__2::char_traits<char>, std::__2::allocator<char> > const&) at gmock-internal-utils.cc:?
#02: testing::internal::UntypedFunctionMockerBase::VerifyAndClearExpectationsLocked() at gmock-spec-builders.cc:?
#03: content::(anonymous namespace)::MockAudioMirroringManager::~MockAudioMirroringManager() at web_contents_audio_input_stream_unittest.cc:?
#04: content::(anonymous namespace)::MockAudioMirroringManager::~MockAudioMirroringManager() at web_contents_audio_input_stream_unittest.cc:?
#05: content::WebContentsAudioInputStreamTest::~WebContentsAudioInputStreamTest() at web_contents_audio_input_stream_unittest.cc:?
#06: content::WebContentsAudioInputStreamTest_MirroringNothing_Test::~WebContentsAudioInputStreamTest_MirroringNothing_Test() at web_contents_audio_input_stream_unittest.cc:?

[  FAILED  ] WebContentsAudioInputStreamTest.MirroringNothingWithTargetChange/1, where GetParam() = true (155 ms)

This suggests some timing-dependency in the test, causing it to flake under Fuchsia, which has different scheduling properties to desktop platform schedulers at present, and for which bots run under nested virtualization.

Assigning to self to disable the test to avoid the immediate issue of try flakes.