--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -1806,17 +1806,20 @@ ContentChild::RecvPBrowserConstructor(PB
 
   static bool hasRunOnce = false;
   if (!hasRunOnce) {
     hasRunOnce = true;
     MOZ_ASSERT(!gFirstIdleTask);
     RefPtr<CancelableRunnable> firstIdleTask = NewCancelableRunnableFunction("FirstIdleRunnable",
                                                                              FirstIdle);
     gFirstIdleTask = firstIdleTask;
-    NS_IdleDispatchToCurrentThread(firstIdleTask.forget());
+    if (NS_FAILED(NS_IdleDispatchToCurrentThread(firstIdleTask.forget()))) {
+      gFirstIdleTask = nullptr;
+      hasRunOnce = false;
+    }
   }
 
   return nsIContentChild::RecvPBrowserConstructor(aActor,
                                                   aTabId,
                                                   aSameTabGroupAs,
                                                   aContext,
                                                   aChromeFlags,
                                                   aCpID,
@@ -2312,16 +2315,17 @@ ContentChild::ActorDestroy(ActorDestroyR
 #ifndef NS_FREE_PERMANENT_DATA
   // In release builds, there's no point in the content process
   // going through the full XPCOM shutdown path, because it doesn't
   // keep persistent state.
   ProcessChild::QuickExit();
 #else
   if (gFirstIdleTask) {
     gFirstIdleTask->Cancel();
+    gFirstIdleTask = nullptr;
   }
 
   nsHostObjectProtocolHandler::RemoveDataEntries();
 
   mAlertObservers.Clear();
 
   mIdleObservers.Clear();