ServiceWorker: Add a check if error handler runs on the right thread

content/browser/service_worker/embedded_worker_instance.cc

 // Copyright 2013 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/browser/service_worker/embedded_worker_instance.h"
 
 #include <utility>
 
 #include "base/bind_helpers.h"
 #include "base/macros.h"
@@ skipping 795 matching lines @@
 }
 
 void EmbeddedWorkerInstance::OnDetached() {
   EmbeddedWorkerStatus old_status = status_;
   ReleaseProcess();
   for (auto& observer : listener_list_)
     observer.OnDetached(old_status);
 }
 
 void EmbeddedWorkerInstance::Detach() {
+  // This could be called on the UI thread if |client_| still be valid when the
+  // message loop on the UI thread gets destructed.

[nhiroki, 2016/11/02 07:59:50]

Making an indirection could be saner than directly calling
EmbeddedWorkerInstance's method on an unexpected thread. For example,

namespace {
void CallDetach(EmbeddedWorkerInstance* instance) {
  // This could be...
  if (!BrowserThread::CurrentlyOn(BrowserThread::IO))
    return;
  instance->Detach();
}
}  // namespace

then

client_.set_connection_error_handler(base::Bind(&CallDetach,
base::Unretained(this)));

[horo, 2016/11/02 08:22:54]

+1

+  // TODO(shimazu): Remove this after https://crbug.com/604762 is fixed
+  if (!BrowserThread::CurrentlyOn(BrowserThread::IO))
+    return;

[horo, 2016/11/02 07:49:12]

Please add DCHECK for mojo sw.

if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
  DCHECK(ServiceWorkerUtils::IsMojoForServiceWorkerEnabled());
  return;
}

   registry_->DetachWorker(process_id(), embedded_worker_id());
   OnDetached();
 }
 
 base::WeakPtr<EmbeddedWorkerInstance> EmbeddedWorkerInstance::AsWeakPtr() {
   return weak_factory_.GetWeakPtr();
 }
 
 bool EmbeddedWorkerInstance::OnMessageReceived(const IPC::Message& message) {
   for (auto& listener : listener_list_) {
@@ skipping 146 matching lines @@
     case SCRIPT_READ_FINISHED:
       return "Script read finished";
     case STARTING_PHASE_MAX_VALUE:
       NOTREACHED();
   }
   NOTREACHED() << phase;
   return std::string();
 }
 
 }  // namespace content