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 "core/dom/ActiveDOMObject.h"
+#include "core/dom/IdleCallbackDeadline.h"
+#include "platform/Timer.h"
+#include "platform/heap/Handle.h"
+#include "wtf/RefCounted.h"
+#include "wtf/RefPtr.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class ExecutionContext;
+class IdleRequestCallback;
+class DocumentLoadTiming;
+
+class ScriptedIdleTaskController : public RefCountedWillBeGarbageCollected<ScriptedIdleTaskController>, public ActiveDOMObject {
+    DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(ScriptedIdleTaskController);
+public:
+    static PassRefPtrWillBeRawPtr<ScriptedIdleTaskController> create(ExecutionContext* context, const DocumentLoadTiming& timing)
+    {
+        return adoptRefWillBeNoop(new ScriptedIdleTaskController(context, timing));
+    }
+    DECLARE_TRACE();
+
+    using CallbackId = int;
+
+    int registerCallback(IdleRequestCallback*, double timeoutMillis);
+    void cancelCallback(CallbackId);
+
+    // ActiveDOMObject interface.
+    void stop() override;
+    void suspend() override;
+    void resume() override;
+    bool hasPendingActivity() const override;
+
+    void callbackFired(CallbackId, double deadlineSeconds, IdleCallbackDeadline::CallbackType);
+
+private:
+    ScriptedIdleTaskController(ExecutionContext*, const DocumentLoadTiming&);
+
+    void runCallback(CallbackId, double deadlineMillis, IdleCallbackDeadline::CallbackType);
+
+    const DocumentLoadTiming& m_timing;
+    WebScheduler* m_scheduler; // Not owned.
+    PersistentHeapHashMapWillBeHeapHashMap<CallbackId, Member<IdleRequestCallback>> m_callbacks;
+    Vector<CallbackId> m_pendingTimeouts;
+    CallbackId m_nextCallbackId;
+    bool m_suspended;
+};
+
+} // namespace blink
+
+#endif // ScriptedIdleTaskController_h