Pass per-frame task runners to Workers (when possible) [2nd try]

third_party/WebKit/Source/core/workers/ParentFrameTaskRunners.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 ParentFrameTaskRunners_h
+#define ParentFrameTaskRunners_h
+
+#include "core/CoreExport.h"
+#include "core/dom/TaskRunnerHelper.h"
+#include "platform/heap/Handle.h"
+#include "wtf/Allocator.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/PtrUtil.h"
+#include <memory>
+
+namespace blink {
+
+class Document;
+class WebTaskRunner;
+
+// Represents a set of task runners of the parent (or associated) document's
+// frame. This could be accessed from worker thread(s) and must be initialized
+// on the parent context thread (i.e. MainThread) on construction time, rather
+// than being done lazily.
+class CORE_EXPORT ParentFrameTaskRunners final {
+    WTF_MAKE_NONCOPYABLE(ParentFrameTaskRunners);
+    USING_FAST_MALLOC(ParentFrameTaskRunners);
+public:
+    static std::unique_ptr<ParentFrameTaskRunners> create(Document* document)
+    {
+        return wrapUnique(new ParentFrameTaskRunners(document));
+    }
+
+    ~ParentFrameTaskRunners();
+
+    WebTaskRunner* get(TaskType);
+
+private:
+    class Observer;
+    explicit ParentFrameTaskRunners(Document*);
+
+    void contextDestroyed();
+
+    WebTaskRunner* m_unthrottledTaskRunner;
+    WebTaskRunner* m_timerTaskRunner;
+    WebTaskRunner* m_loadingTaskRunner;
+
+    // A ContextLifecycleObserver for resetting task runners when the
+    // parent context is detached.
+    Persistent<Observer> m_observer;

[haraken, 2016/08/11 14:57:43]

It would be slightly better to put ParentFrameTaskRunners on Oilpan's heap to
avoid the Persistent handle and a raw back pointer from the Observer object.

[kinuko, 2016/08/11 23:21:37]

Done.

+};
+
+} // namespace blink
+
+#endif // ParentFrameTaskRunners_h