https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.10%20Tests
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.12%20Tests

Failing to start test server?
Might be related to  Issue 910378  (on Linux), but traces are different.

https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8928488302162992960/+/steps/net_unittests_on__none__GPU_on_Mac_on_Mac-10.10/0/logs/SSLClientSocketReadTest.Read__x2f_1/0

[ RUN      ] SSLClientSocketReadTest.Read/1
[5492:779:1129/134104.981145:1943966006550:ERROR:local_test_server_posix.cc(79)] poll() timed out; bytes_read=0
[5492:779:1129/134104.981189:1943966041833:ERROR:local_test_server_posix.cc(167)] Could not read server_data_len
[5492:779:1129/134104.984682:1943969549593:ERROR:ssl_client_socket_unittest.cc(830)] Could not start SpawnedTestServer
../../net/socket/ssl_client_socket_unittest.cc:1444: Failure
Value of: StartTestServer(SpawnedTestServer::SSLOptions())
  Actual: false
Expected: true
Stack trace:
0   net_unittests                       0x00000001065c350b testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop(int) + 91
1   net_unittests                       0x00000001065c2ec9 testing::internal::AssertHelper::operator=(testing::Message const&) const + 89
2   net_unittests                       0x0000000105975a75 net::SSLClientSocketReadTest_Read_Test::TestBody() + 517

[  FAILED  ] SSLClientSocketReadTest.Read/1, where GetParam() = true (10031 ms)