--- a/dom/media/gmp/GMPServiceChild.cpp
+++ b/dom/media/gmp/GMPServiceChild.cpp
@@ -353,19 +353,16 @@ GMPServiceChild::GetBridgedGMPContentPar
   mContentParents.Get(aOtherPid, getter_AddRefs(parent));
 
   if (parent) {
     return parent.forget();
   }
 
   MOZ_ASSERT(aOtherPid == endpoint.OtherPid());
 
-  nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
-  MOZ_ASSERT(mainThread);
-
   parent = new GMPContentParent();
 
   DebugOnly<bool> ok = endpoint.Bind(parent);
   MOZ_ASSERT(ok);
 
   mContentParents.Put(aOtherPid, parent);
 
   return parent.forget();