b=161394 Fix crash in debug builds

r=javi sr=alecf

security/manager/boot/src/nsSecureBrowserUIImpl.cpp

@@ -1149,11 +1149,13 @@ nsSecureBrowserUIImpl::OnSecurityChange(nsIWebProgress *aWebProgress,
   nsCOMPtr<nsIURI> aURI;
   channel->GetURI(getter_AddRefs(aURI));
   
+  if (aURI) {
     nsCAutoString temp;
     aURI->GetSpec(temp);
     PR_LOG(gSecureDocLog, PR_LOG_DEBUG,
            ("SecureUI:%p: OnSecurityChange: (%x) %s\n", this,
             state, temp.get()));
+  }
 #endif
 
   return NS_OK;