See http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20-%20chromium.org&tests=fast%2Fframes%2Fseamless%2Fseamless-form-post-override.html%2Cfast%2Fframes%2Fseamless%2Fseamless-window-location-replace.html&showExpectations=true A typical failing result looks like: FAIL frames[0].frames[0].document.body.textContent should be DONE . Threw exception TypeError: Cannot read property 'textContent' of null Not clear to me how long these have been flaky. ->eric since he originally added the tests and thus might know how to triage this.
The more I look at this the more I think there's a general problem with tests involving frame navigation. Here are some more tests that are failing on Mac/Win: http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20-%20chromium.org&tests=http%2Ftests%2Fnavigation%2Flockedhistory-iframe.html%2Chttp%2Ftests%2Fsecurity%2FmixedContent%2Fdata-url-iframe-in-main-frame.html%2Cplatform%2Fchromium%2Fhttp%2Ftests%2Fsecurity%2FmixedContent%2Finsecure-image-in-main-frame-blocked.html&showExpectations=true CCing abarth since he knows something about navigation, I think.
*** Bug 93569 has been marked as a duplicate of this bug. ***
I believe abarth is on vacation through end of next week.