if (mUpdateBatchNest != 0)  return NS_OK;
if (mObservers) { nsresult rv;
nsBookmarksService::OnUnassert(nsIRDFDataSource* aDataSource,                   nsIRDFResource* aSource,                   nsIRDFResource* aProperty,                   nsIRDFNode* aTarget){    if (mUpdateBatchNest != 0)  return NS_OK;    PRInt32 count = mObservers.Count();    for (PRInt32 i = 0; i < count; ++i)    {        (void) mObservers[i]->OnUnassert(this, aSource, aProperty, aTarget);    }    return NS_OK;}