Link to Analysis: https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVyrQELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCJ3Y2hyb21pdW0ud2luL1dpbjcgVGVzdHMgKDEpLzgyNjY3L2NvbXBvbmVudHNfdW5pdHRlc3RzL1UzTnNRMkZ6ZEZOdlkydGxkRlJsYzNRdVZHVnpkRU52Ym01bFkzUkZibVJVYjBWdVpGZHBkR2hTWldGc1UxTk0MCxITTWFzdGVyRmxha2VBbmFseXNpcxgCDA

It assumed this patch is the reason 
https://chromium-review.googlesource.com/c/chromium/src/+/1167509
this cannot be true because the mentioned CL only enabled some Bookmark Sync integration tests. Therefore, it cannot cause that SslCastSocketTest.TestConnectEndToEndWithRealSSL to be flaky.