service worker: Attempt to send WorkerStopped before ProviderDestroyed.

content/renderer/service_worker/embedded_worker_instance_client_impl.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/service_worker/embedded_worker_instance_client_impl.h"
 
 #include <memory>
 
 #include "base/strings/utf_string_conversions.h"
 #include "content/child/scoped_child_process_reference.h"
@@ skipping 10 matching lines @@
 void EmbeddedWorkerInstanceClientImpl::Create(
     EmbeddedWorkerDispatcher* dispatcher,
     mojo::InterfaceRequest<mojom::EmbeddedWorkerInstanceClient> request) {
   // This won't be leaked because the lifetime will be managed internally.
   new EmbeddedWorkerInstanceClientImpl(dispatcher, std::move(request));
 }
 
 void EmbeddedWorkerInstanceClientImpl::StopWorkerCompleted() {
   DCHECK(embedded_worker_id_);
   DCHECK(stop_callback_);
+  TRACE_EVENT0("ServiceWorker",
+               "EmbeddedWorkerInstanceClientImpl::StopWorkerCompleted");
+  // TODO(falken): The signals to the browser should be in the order:
+  // (1) WorkerStopped (via stop_callback_)
+  // (2) ProviderDestroyed (via UnregisterWorker destroying
+  //     WebEmbeddedWorkerImpl)
+  // But this ordering is currently not guaranteed since the Mojo pipes are
+  // different. https://crbug.com/676526
+  stop_callback_.Run();
+  stop_callback_.Reset();
   dispatcher_->UnregisterWorker(embedded_worker_id_.value());
   embedded_worker_id_.reset();
-  stop_callback_.Run();
-  TRACE_EVENT0("ServiceWorker",
-               "EmbeddedWorkerInstanceClientImpl::StopWorkerCompleted");
-  stop_callback_.Reset();
   wrapper_ = nullptr;
 }
 
 void EmbeddedWorkerInstanceClientImpl::StartWorker(
     const EmbeddedWorkerStartParams& params,
     mojom::ServiceWorkerEventDispatcherRequest dispatcher_request) {
   DCHECK(ChildThreadImpl::current());
   DCHECK(!wrapper_);
   TRACE_EVENT0("ServiceWorker",
                "EmbeddedWorkerInstanceClientImpl::StartWorker");
@@ skipping 36 matching lines @@
 }
 
 EmbeddedWorkerInstanceClientImpl::~EmbeddedWorkerInstanceClientImpl() {}
 
 void EmbeddedWorkerInstanceClientImpl::OnError() {
   // Removes myself if it's owned by myself.
   temporal_self_.reset();
 }
 
 }  // namespace content