If WebKit is allowed to loop various kinds of media content for long periods of time, we sometimes run into a deadlock between AVFoundationCF and the AVFWrapper mutex used to protect individual AVF playback instances.
This deadlock happens because in some cases a notification will trigger on the main thread, which will immediately begin executing handler content without releasing the AVFWrapper container mutex used to prevent deleting AVFWrapper instances while they are still being used.
For Windows, we should tell WebKit to always invoke these handlers asynchronously so that we do not encounter this deadlock.
Created attachment 232901 [details]
Note: The EWS error is due to a problem on the build machine, not this patch.
Committed r169842: <http://trac.webkit.org/changeset/169842>