Backed out changeset f3290b0f20cc (bug 1323983)

dom/ipc/TabParent.cpp

@@ -1248,9 +1248,8 @@ public:
                      const char* aTopic,
                      const char16_t* aData) override
   {
-    if (!mTabParent || !mObserverId) {
-      // We already sent the notification, or we don't actually need to
-      // send any notification at all.
+    if (!mTabParent) {
+      // We already sent the notification
       return NS_OK;
     }