https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/142774 (note that the build succeeds because the test flaked on the 'without patch' run of webkit_layout_tests).

It appears that the test timed out:

https://chromium-swarm.appspot.com/task?id=3ccae05082deae10&refresh=10&show_raw=1

17:34:14.926 3716 [3/5] http/tests/devtools/cache-storage/cache-data.js failed unexpectedly (test timed out)

It also flakes on the real bots as well, mostly quietly. E.g. see https://test-results.appspot.com/data/layout_results/WebKit_Mac10_11/31655/layout-test-results/results.html, choose 'Flaky', and there is an entry for this test timing out.