Add a return when StopWorker is called after service worker is stopped

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 26 matching lines @@
 
 void EmbeddedWorkerInstanceClientImpl::StopWorkerCompleted() {
   DCHECK(embedded_worker_id_);
   DCHECK(stop_callback_);
   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,
     service_manager::mojom::InterfaceProviderPtr browser_interfaces,
     service_manager::mojom::InterfaceProviderRequest renderer_request) {
   DCHECK(ChildThreadImpl::current());
   TRACE_EVENT0("ServiceWorker",
                "EmbeddedWorkerInstanceClientImpl::StartWorker");
   embedded_worker_id_ = params.embedded_worker_id;
   remote_interfaces_.Bind(std::move(browser_interfaces));
   renderer_request_ = std::move(renderer_request);
 
   std::unique_ptr<EmbeddedWorkerDispatcher::WorkerWrapper> wrapper =
       dispatcher_->StartWorkerContext(
           params, base::MakeUnique<ServiceWorkerContextClient>(
                       params.embedded_worker_id,
                       params.service_worker_version_id, params.scope,
                       params.script_url, params.worker_devtools_agent_route_id,
                       std::move(temporal_self_)));
   wrapper_ = wrapper.get();

[nhiroki, 2016/11/11 11:24:10]

DCHECK(!wrapper_);

   dispatcher_->RegisterWorker(params.embedded_worker_id, std::move(wrapper));
 }
 
 void EmbeddedWorkerInstanceClientImpl::StopWorker(
     const StopWorkerCallback& callback) {
   DCHECK(ChildThreadImpl::current());
   DCHECK(embedded_worker_id_);
   // StopWorker is possible to be called twice.
-  if (stop_callback_) {
+  if (stop_callback_ || !wrapper_) {
     LOG(WARNING) << "Got StopWorker for stopping worker";
     return;
   }
   TRACE_EVENT0("ServiceWorker", "EmbeddedWorkerInstanceClientImpl::StopWorker");
   stop_callback_ = std::move(callback);
   dispatcher_->RecordStopWorkerTimer(embedded_worker_id_.value());
   wrapper_->worker()->terminateWorkerContext();
 }
 
 EmbeddedWorkerInstanceClientImpl::EmbeddedWorkerInstanceClientImpl(
     EmbeddedWorkerDispatcher* dispatcher,
     mojo::InterfaceRequest<mojom::EmbeddedWorkerInstanceClient> request)
     : dispatcher_(dispatcher),
       binding_(this, std::move(request)),
       temporal_self_(std::unique_ptr<EmbeddedWorkerInstanceClientImpl>(this)) {

[nhiroki, 2016/11/11 11:24:10]

How about initializing |wrapper_| with nullptr?

   binding_.set_connection_error_handler(base::Bind(
       &EmbeddedWorkerInstanceClientImpl::OnError, base::Unretained(this)));
 }
 
 EmbeddedWorkerInstanceClientImpl::~EmbeddedWorkerInstanceClientImpl() {}
 
 void EmbeddedWorkerInstanceClientImpl::OnError() {
   // Removes myself if it's owned by myself.
   temporal_self_.reset();
 }
 
 }  // namespace content