Delegate WebSocket message handlers to the loading task runner

content/child/websocket_message_filter.h

+// Copyright 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.
+
+#ifndef CONTENT_CHILD_WEBSOCKET_MESSAGE_FILTER_H_
+#define CONTENT_CHILD_WEBSOCKET_MESSAGE_FILTER_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "ipc/message_filter.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace content {
+
+class WebSocketDispatcher;
+
+// Delegates IPC messages to a WebSocketDispatcher on the loading task queue
+// instead of the default task queue.
+//
+// Background: When we want to suspend V8 execution, we need to suspend task
+// queues. However, the default task queue can't be suspended because it'd be

[yhirano, 2016/05/25 10:39:52]

Is this comment needed?

[hajimehoshi, 2016/05/25 12:05:02]

As we discussed offline, this explanation is in the description in this CL and
it's enough. Done.

+// dangarous. As WebSocket IPC message dispatching might call V8 functions, we
+// need to delegate this dispatch to another task queue like the loading task
+// queue.
+class WebSocketMessageFilter : public IPC::MessageFilter {
+ public:
+  WebSocketMessageFilter(WebSocketDispatcher* websocket_dispatcher);

[kinuko, 2016/05/25 09:30:53]

nit: explicit

[hajimehoshi, 2016/05/25 12:05:02]

Done.

+
+  // IPC::MessageFilter implementation.
+  bool OnMessageReceived(const IPC::Message& message) override;
+
+  void SetLoadingTaskRunner(
+      scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner) {
+    loading_task_runner_ = loading_task_runner;
+  }
+
+ private:
+  ~WebSocketMessageFilter() override;
+
+  scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner_;
+  WebSocketDispatcher* websocket_dispatcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebSocketMessageFilter);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_CHILD_WEBSOCKET_MESSAGE_FILTER_H_