Looks likely to be cross-platform. Reproduced locally with:

ninja -C out/fuch content_unittests -j3000 && out/fuch/bin/run_content_unittests --gtest_filter=LegacyInputRouterImplTest.AckedTouchEventState --gtest_repeat=1000 --gtest_break_on_failure --test-launcher-jobs=1

after repeats.

[00033.425] 29477.29504> [ RUN      ] LegacyInputRouterImplTest.AckedTouchEventState
[00033.429] 29477.29504> ../../content/browser/renderer_host/input/legacy_input_router_impl_unittest.cc:1076: Failure
[00033.429] 29477.29504> Value of: success
[00033.429] 29477.29504>   Actual: false
[00033.429] 29477.29504> Expected: true
[00033.429] 29477.29504> Failed on step: 3
[00033.429] 01119.01152> <== fatal exception: process content_unittests[29477] thread initial-thread[29504]
[00033.429] 01119.01152> <== fatal page fault, PC at 0x1919ae232788
[00033.429] 01119.01152>  CS:                   0 RIP:     0x1919ae232788 EFL:            0x10246 CR2:                  0
[00033.429] 01119.01152>  RAX:                  0 RBX:     0x62f4902038c0 RCX:                  0 RDX:                0x5
[00033.429] 01119.01152>  RSI:     0x1a9f89fa1ad0 RDI:     0x62f82c185f30 RBP:     0x1a9f89fa1cb0 RSP:     0x1a9f89fa1a30
[00033.429] 01119.01152>   R8:               0x10  R9:                0x1 R10:     0x63b201e8a640 R11:              0x246
[00033.429] 01119.01152>  R12:         0x6c945dd1 R13:     0x71e08e0fbce0 R14:     0x62f4902038c0 R15:     0x62f4902038c0
[00033.429] 01119.01152>  errc:               0x6
[00033.429] 01119.01152> bottom of user stack:
[00033.429] 01119.01152> 0x00001a9f89fa1a30: 89fa1b38 00001a9f 2bffb840 000062f8 |8.......@..+.b..|
[00033.429] 01119.01152> 0x00001a9f89fa1a40: 89fa1ab8 00001a9f 00000000 00000001 |................|
[00033.429] 01119.01152> 0x00001a9f89fa1a50: a8b3891c 00001919 89fa1cf1 00000434 |............4...|
[00033.429] 01119.01152> 0x00001a9f89fa1a60: 89fa1c10 00001a9f 00000000 00000000 |................|
[00033.429] 01119.01152> 0x00001a9f89fa1a70: 89fa1cf0 00001a9f 89fa1cf1 00001a9f |................|
[00033.429] 01119.01152> 0x00001a9f89fa1a80: 89fa1cf0 00001a9f 89fa1b58 00001a9f |........X.......|
[00033.429] 01119.01152> 0x00001a9f89fa1a90: 89fa1b58 00001a9f 00000030 00000000 |X.......0.......|
[00033.429] 01119.01152> 0x00001a9f89fa1aa0: 00000028 00000000 89fa1b58 00001a9f |(.......X.......|
[00033.429] 01119.01152> 0x00001a9f89fa1ab0: bac672e8 00001919 00000091 00000000 |.r..............|
[00033.429] 01119.01152> 0x00001a9f89fa1ac0: 00000042 00000000 2bffb840 000062f8 |B.......@..+.b..|
[00033.429] 01119.01152> 0x00001a9f89fa1ad0: 00000001 00001919 00000051 00000000 |........Q.......|
[00033.429] 01119.01152> 0x00001a9f89fa1ae0: 0000004e 00000000 2c1aa650 000062f8 |N.......P..,.b..|
[00033.429] 01119.01152> 0x00001a9f89fa1af0: 00000434 00001a9f 00000051 00000000 |4.......Q.......|
[00033.429] 01119.01152> 0x00001a9f89fa1b00: 00000042 00000000 2c1aa6f0 000062f8 |B..........,.b..|
[00033.429] 01119.01152> 0x00001a9f89fa1b10: 00000051 00000000 00000042 00000000 |Q.......B.......|
[00033.429] 01119.01152> 0x00001a9f89fa1b20: 2c1aa740 000062f8 89fa1cf0 00001a9f |@..,.b..........|
[00033.429] 01119.01152> arch: x86_64
[00033.429] 01119.01152> dso: id=f235c1e16717d9197e499a200425e0681468b830 base=0x7df2db6bd000 name=libfdio.so
[00033.429] 01119.01152> dso: id=4e555334ce701b327433bb28771402652496af06 base=0x6233157cd000 name=liblaunchpad.so
[00033.429] 01119.01152> dso: id=6059863b129a49d829760aa4be72cc3742a085c6 base=0x5dc4cffbc000 name=<vDSO>
[00033.429] 01119.01152> dso: id=5ddf965ecef4f7eaba5aa9b7b240503f27a2595a base=0x4694d9441000 name=libc.so
[00033.429] 01119.01152> dso: id=241ca570db3c8f9b base=0x1919a8ae4000 name=app:content_unittests
#01: testing::UnitTest::AddTestPartResult(testing::TestPartResult::Type, char const*, int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) at third_party/googletest/src/googletest/src/gtest.cc:4184
#02: testing::internal::AssertHelper::operator=(testing::Message const&) const at third_party/googletest/src/googletest/src/gtest.cc:376
#03: content::LegacyInputRouterImplTest_AckedTouchEventState_Test::TestBody() at content/browser/renderer_host/input/legacy_input_router_impl_unittest.cc:1076
#04: void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) at third_party/googletest/src/googletest/src/gtest.cc:2400
#05: void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) at third_party/googletest/src/googletest/src/gtest.cc:2453
#06: pc 0x1919ae242876 sp 0x1a9f89fa3190 (app:content_unittests,0x575e876)
#07: pc 0x1919ae2433cd sp 0x1a9f89fa3200 (app:content_unittests,0x575f3cd)
#08: testing::TestCase::Run() at third_party/googletest/src/googletest/src/gtest.cc:2771
#09: testing::internal::UnitTestImpl::RunAllTests() at third_party/googletest/src/googletest/src/gtest.cc:4676
#10: bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) at third_party/googletest/src/googletest/src/gtest.cc:2400
#11: bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) at third_party/googletest/src/googletest/src/gtest.cc:2453
#12: testing::UnitTest::Run() at third_party/googletest/src/googletest/src/gtest.cc:4285
#13: RUN_ALL_TESTS() at third_party/googletest/src/googletest/include/gtest/gtest.h:2237
#14: base::TestSuite::Run() at base/test/test_suite.cc:270
#15: content::UnitTestTestSuite::Run() at content/public/test/unittest_test_suite.cc:45
#16: int base::internal::FunctorTraits<int (content::UnitTestTestSuite::*)(), void>::Invoke<content::UnitTestTestSuite*>(int (content::UnitTestTestSuite::*)(), content::UnitTestTestSuite*&&) at base/bind_internal.h:194
#17: int base::internal::InvokeHelper<false, int>::MakeItSo<int (content::UnitTestTestSuite::* const&)(), content::UnitTestTestSuite*>(int (content::UnitTestTestSuite::* const&)(), content::UnitTestTestSuite*&&) at base/bind_internal.h:277
#18: int base::internal::Invoker<base::internal::BindState<int (content::UnitTestTestSuite::*)(), base::internal::UnretainedWrapper<content::UnitTestTestSuite> >, int ()>::RunImpl<int (content::UnitTestTestSuite::* const&)(), std::__1::tuple<base::internal::UnretainedWrapper<content::UnitTestTestSuite> > const&, 0ul>(int (content::UnitTestTestSuite::* const&)(), std::__1::tuple<base::internal::UnretainedWrapper<content::UnitTestTestSuite> > const&, std::__1::integer_sequence<unsigned long, 0ul>) at base/bind_internal.h:349
#19: base::internal::Invoker<base::internal::BindState<int (content::UnitTestTestSuite::*)(), base::internal::UnretainedWrapper<content::UnitTestTestSuite> >, int ()>::Run(base::internal::BindStateBase*) at base/bind_internal.h:331
#20: base::RepeatingCallback<int ()>::Run() const & at base/callback.h:92
#21: base::(anonymous namespace)::LaunchUnitTestsInternal(base::RepeatingCallback<int ()> const&, unsigned long, int, bool, base::RepeatingCallback<void ()> const&) at base/test/launcher/unit_test_launcher.cc:216
#22: base::LaunchUnitTests(int, char**, base::RepeatingCallback<int ()> const&) at base/test/launcher/unit_test_launcher.cc:475
#23: main at content/test/run_all_unittests.cc:20
#24: pc 0x4694d945cebe sp 0x1a9f89fa3fe0 (libc.so,0x1bebe)
#25: pc 0 sp 0x1a9f89fa4000
[00033.443] 02352.02379> [1/1] LegacyInputRouterImplTest.AckedTouchEventState (CRASHED)
[00033.443] 02352.02379> 1 test crashed:
[00033.443] 02352.02379>     LegacyInputRouterImplTest.AckedTouchEventState (../../content/browser/renderer_host/input/legacy_input_router_impl_unittest.cc:997)