Bug 1870423 - Take always ownership of aRunnable in RemoteLazyInputStreamThread::Dispatch. r=dom-storage-reviewers,asuth

Differential Revision: https://phabricator.services.mozilla.com/D196765

dom/file/ipc/RemoteLazyInputStreamThread.cpp

@@ -147,12 +147,15 @@ RemoteLazyInputStreamThread::IsOnCurrentThread(bool* aRetval) {
 NS_IMETHODIMP
 RemoteLazyInputStreamThread::Dispatch(already_AddRefed<nsIRunnable> aRunnable,
                                       uint32_t aFlags) {
+  nsCOMPtr<nsIRunnable> runnable(aRunnable);
+
   if (RLISThreadIsInOrBeyondShutdown()) {
+    // nsIEventTarget::Dispatch must leak the runnable if the dispatch fails.
+    (void)runnable.forget();
+
     return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
   }
 
-  nsCOMPtr<nsIRunnable> runnable(aRunnable);
-
   StaticMutexAutoLock lock(gRemoteLazyThreadMutex);
 
   return mThread->Dispatch(runnable.forget(), aFlags);