ServiceWorker: check if StopWorker is called twice

content/renderer/service_worker/embedded_worker_dispatcher.cc

Index: content/renderer/service_worker/embedded_worker_dispatcher.cc
diff --git a/content/renderer/service_worker/embedded_worker_dispatcher.cc b/content/renderer/service_worker/embedded_worker_dispatcher.cc
index 2a9251aec82518e319eac0c856911049f5d12653..ddbb8012b13cd3e0b8140f2aaa0c85951f66bb30 100644
--- a/content/renderer/service_worker/embedded_worker_dispatcher.cc
+++ b/content/renderer/service_worker/embedded_worker_dispatcher.cc
@@ -77,6 +77,11 @@ void EmbeddedWorkerDispatcher::OnStartWorker(
 void EmbeddedWorkerDispatcher::OnStopWorker(int embedded_worker_id) {
   TRACE_EVENT0("ServiceWorker", "EmbeddedWorkerDispatcher::OnStopWorker");
   WorkerWrapper* wrapper = workers_.Lookup(embedded_worker_id);
+  // OnStopWorker is possible to be called twice.
+  if (!wrapper) {
+    LOG(WARNING) << "Got OnStopWorker for nonexistent worker";
+    return;
+  }
   DCHECK(wrapper);

[nhiroki, 2016/10/20 09:22:11]

This DCHECK is obvious. Can you remove this?

[shimazu, 2016/10/21 01:17:02]

Done.

   // This should eventually call WorkerContextDestroyed. (We may need to post
   // a delayed task to forcibly abort the worker context if we find it