Do not try to load empty images

chrome/browser/notifications/notification_ui_manager_mac.mm

Index: chrome/browser/notifications/notification_ui_manager_mac.mm
diff --git a/chrome/browser/notifications/notification_ui_manager_mac.mm b/chrome/browser/notifications/notification_ui_manager_mac.mm
index f5fdf4a104605deda95e693d3c4c28935a558ca8..b8c5eb3d293f14bdb108c264d53fdefa62b3bbf8 100644
--- a/chrome/browser/notifications/notification_ui_manager_mac.mm
+++ b/chrome/browser/notifications/notification_ui_manager_mac.mm
@@ -121,7 +121,8 @@ void NotificationUIManagerMac::Add(const Notification& notification,
 
   // Some functionality is only available in 10.9+ or requires private APIs
   // Icon
-  if ([toast respondsToSelector:@selector(_identityImage)]) {
+  if ([toast respondsToSelector:@selector(_identityImage)] &&
+      !notification.icon().IsEmpty()) {
     [toast setValue:notification.icon().ToNSImage() forKey:@"_identityImage"];
     [toast setValue:@NO forKey:@"_identityImageHasBorder"];
   }