ServiceWorker: Fix data race in shutdown sequence

content/renderer/render_thread_impl.cc

 // Copyright (c) 2012 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/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 631 matching lines @@
   RemoveFilter(audio_message_filter_.get());
   audio_message_filter_ = NULL;
 
   compositor_thread_.reset();
   input_handler_manager_.reset();
   if (input_event_filter_.get()) {
     RemoveFilter(input_event_filter_.get());
     input_event_filter_ = NULL;
   }
 
-  // RemoveEmbeddedWorkerRoute may be called while deleting
-  // EmbeddedWorkerDispatcher. So it must be deleted before deleting
-  // RenderThreadImpl.
-  embedded_worker_dispatcher_.reset();
-
   // Ramp down IDB before we ramp down WebKit (and V8), since IDB classes might
   // hold pointers to V8 objects (e.g., via pending requests).
   main_thread_indexed_db_dispatcher_.reset();
 
   main_thread_compositor_task_runner_ = NULL;
 
   if (blink_platform_impl_)
     blink::shutdown();
 
+  // RemoveEmbeddedWorkerRoute may be called while deleting
+  // EmbeddedWorkerDispatcher. So it must be deleted before deleting
+  // RenderThreadImpl.
+  embedded_worker_dispatcher_.reset();

[horo, 2014/10/27 13:38:25]

Could you please write the comments about the race here?

[Kunihiko Sakamoto, 2014/10/28 01:12:27]

Done.

+
   lazy_tls.Pointer()->Set(NULL);
 
   // TODO(port)
 #if defined(OS_WIN)
   // Clean up plugin channels before this thread goes away.
   NPChannelBase::CleanupChannels();
 #endif
 }
 
 bool RenderThreadImpl::Send(IPC::Message* msg) {
@@ skipping 908 matching lines @@
   hidden_widget_count_--;
 
   if (!GetContentClient()->renderer()->RunIdleHandlerWhenWidgetsHidden()) {
     return;
   }
 
   ScheduleIdleHandler(kLongIdleHandlerDelayMs);
 }
 
 }  // namespace content