If the previous document and the current document have the same origin, the IHTMLPerformanceTiming::unloadEventEnd property must return the time immediately after the user agent finishes the unload event of the previous document. If there is no previous document or the previous document has a different origin than the current document, or the unload is not yet completed, this attribute must return zero.
HRESULT value = object.get_unloadEventEnd(ULONGLONG* p);
An ULONGLONG value that represents the time immediately after the user agent finishes the unload event of the previous document.
- Navigation Timing, Section 4.2
The value reported by the IHTMLPerformanceTiming::unloadEventEnd property represents the number of milliseconds between the recorded time and midnight January 1, 1970 (UTC).