The architecture of some WebKit clients cause them to create multiple process pools, causing new HashTables and message queues to be created. This also results in the potential loss of some load statistics since the old data is thrown out. The interface to the ResourceLoadObserver should be refined to avoid this.
<rdar://problem/33086699>
This turned out to be fixed by Bug 174189. Committed r219203: <http://trac.webkit.org/changeset/219203>