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 Additional notifications for history observers.  Your observer will not be
 notified for this unless it can QI to this interface.

 This interface was added after the binary compatibility freeze, so it lives
 in a separate interface for 1.9.1.  In future releases, the methods found in
 this interface will be in nsINavHistoryObserver.
[scriptable, uuid(c1945447-a94f-4134-80c5-7fe48ef00178)]
interface nsINavHistoryObserver_MOZILLA_1_9_1_ADDITIONS : nsISupports

Methods

 This page and all of its visits are about to be deleted.  Note: the page
 may not necessarily have actually existed for this function to be called.

 @param aURI
        The URI being deleted.
void onBeforeDeleteURI(in nsIURI aURI)