[Merge to M51] ServiceWorker: Remove a bad IPC message check on postMessage()

content/browser/service_worker/service_worker_dispatcher_host.cc

Index: content/browser/service_worker/service_worker_dispatcher_host.cc
diff --git a/content/browser/service_worker/service_worker_dispatcher_host.cc b/content/browser/service_worker/service_worker_dispatcher_host.cc
index d15732d41aa8e4167afd2a5084f5c33d3a12e276..eeb6b69cdaef08283ec8f7638321f53d7f9eeaa2 100644
--- a/content/browser/service_worker/service_worker_dispatcher_host.cc
+++ b/content/browser/service_worker/service_worker_dispatcher_host.cc
@@ -696,7 +696,8 @@ void ServiceWorkerDispatcherHost::OnPostMessageToWorker(
   ServiceWorkerProviderHost* sender_provider_host =
       GetContext()->GetProviderHost(render_process_id_, provider_id);
   if (!sender_provider_host) {
-    bad_message::ReceivedBadMessage(this, bad_message::SWDH_POST_MESSAGE);
+    // This may occur when destruction of the sender provider overtakes
+    // postMessage() because of thread hopping on WebServiceWorkerImpl.
     return;
   }