Add WorkerScriptLoaded message to support attaching DevTools while starting ServiceWorker.

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 f36af0737b6e5062079a0d393a7d30db98c4f7c2..486a889fdeb9edf82a789628024e4f3099bd9b47 100644
--- a/content/browser/service_worker/service_worker_dispatcher_host.cc
+++ b/content/browser/service_worker/service_worker_dispatcher_host.cc
@@ -106,6 +106,8 @@ bool ServiceWorkerDispatcherHost::OnMessageReceived(
                         OnSetHostedVersionId)
     IPC_MESSAGE_HANDLER(ServiceWorkerHostMsg_PostMessage,
                         OnPostMessage)
+    IPC_MESSAGE_HANDLER(EmbeddedWorkerHostMsg_WorkerScriptLoaded,
+                        OnWorkerScriptLoaded)
     IPC_MESSAGE_HANDLER(EmbeddedWorkerHostMsg_WorkerStarted,
                         OnWorkerStarted)
     IPC_MESSAGE_HANDLER(EmbeddedWorkerHostMsg_WorkerStopped,
@@ -330,6 +332,13 @@ void ServiceWorkerDispatcherHost::RegistrationComplete(
   RegisterServiceWorkerHandle(handle.Pass());
 }
 
+void ServiceWorkerDispatcherHost::OnWorkerScriptLoaded(int embedded_worker_id) {
+  if (!context_)
+    return;
+  context_->embedded_worker_registry()->OnWorkerScriptLoaded(
+      render_process_id_, embedded_worker_id);
+}
+
 void ServiceWorkerDispatcherHost::OnWorkerStarted(
     int thread_id, int embedded_worker_id) {
   if (!context_)