SBNavigationObserverBrowserTest.DirectDownloadNoReferrerTargetBlank on browser_side_navigation_browser_tests on Mac-10.11 is flaky according to an analysis by Findit:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVy6AELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKxAWNocm9taXVtLm1hYy9NYWMxMC4xMSBUZXN0cy8xMTUyNS9icm93c2VyX3NpZGVfbmF2aWdhdGlvbl9icm93c2VyX3Rlc3RzIG9uIE1hYy0xMC4xMS9VMEpPWVhacFoyRjBhVzl1VDJKelpYSjJaWEpDY205M2MyVnlWR1Z6ZEM1RWFYSmxZM1JFYjNkdWJHOWhaRTV2VW1WbVpYSnlaWEpVWVhKblpYUkNiR0Z1YXc9PQwLEhNNYXN0ZXJGbGFrZUFuYWx5c2lzGAEM

The suggested culprit CL is https://codereview.chromium.org/2821473002