Implement requestIdleCallback API

Source/core/dom/ScriptedIdleTaskController.h

+// Copyright 2015 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 ScriptedIdleTaskController_h
+#define ScriptedIdleTaskController_h
+
+#include "platform/heap/Handle.h"
+#include "wtf/RefCounted.h"
+#include "wtf/RefPtr.h"
+
+namespace blink {
+
+class Document;
+class IdleRequestCallback;
+
+class ScriptedIdleTaskController : public RefCountedWillBeGarbageCollected<ScriptedIdleTaskController> {
+    DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(ScriptedIdleTaskController);
+public:
+    static PassRefPtrWillBeRawPtr<ScriptedIdleTaskController> create(Document* document)
+    {
+        return adoptRefWillBeNoop(new ScriptedIdleTaskController(document));
+    }
+    DECLARE_TRACE();
+    void clearDocumentPointer() { m_document = nullptr; }
+
+    using CallbackId = int;
+
+    int registerCallback(IdleRequestCallback*);
+    void cancelCallback(CallbackId);
+
+private:
+    class IdleRequestCallbackWrapper : public RefCounted<IdleRequestCallbackWrapper> {
+    public:
+        static PassRefPtr<IdleRequestCallbackWrapper> create(IdleRequestCallback* callback)
+        {
+            return adoptRef(new IdleRequestCallbackWrapper(callback));
+        }
+        ~IdleRequestCallbackWrapper();
+
+        static void runCallback(PassRefPtr<IdleRequestCallbackWrapper>, double deadlineSeconds);
+
+    private:
+        explicit IdleRequestCallbackWrapper(IdleRequestCallback*);
+
+        Persistent<IdleRequestCallback> m_callback;
+    };
+
+    explicit ScriptedIdleTaskController(Document*);
+
+    void runCallback(IdleRequestCallback*, double deadlineSeconds);
+
+    RawPtrWillBeMember<Document> m_document;
+    PersistentHeapHashMapWillBeHeapHashMap<CallbackId, Member<IdleRequestCallback>> m_callbacks;
+    CallbackId m_nextCallbackId;
+};
+
+} // namespace blink
+
+#endif // ScriptedIdleTaskController_h