appears to be because the QT plugin is missing, which is a bit odd; I thought we required that to be installed, but maybe something changed? http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpectations=true&group=%40ToT%20-%20chromium.org&tests=plugins%2Fembed-attributes-style.html
The win failures are only because the dotted borders changed slightly (the revisions that caused the failure are here: http://trac.webkit.org/log/?verbose=on&rev=84278&stop_rev=84273 ). Linux looks like it just needs a rebaseline too since it never had a quicktime plugin (but perhaps whoever added the initial baselines had mozilla-totem installed or something).
Landed new baselines in http://trac.webkit.org/changeset/84674