Initial ResizeObserver implementation

third_party/WebKit/Source/core/observer/ResizeObserverController.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 ResizeObserverController_h
+#define ResizeObserverController_h
+
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class ResizeObserver;
+
+// ResizeObserverController keeps track of all ResizeObservers
+// in a single Document.
+class ResizeObserverController : public GarbageCollected<ResizeObserverController> {
+
+public:
+
+    static const size_t kRenderLoopLimit = 16;

[eae, 2016/07/13 23:39:47]

A comment explaining the limit would be helpful.

[atotic1, 2016/07/15 01:43:17]

This limit will go away in the final checkin.

+
+    ResizeObserverController();
+
+    void addObserver(ResizeObserver&);
+    bool gatherObservations();
+    void deliverObservations();
+    void clearObservations();
+
+    DECLARE_TRACE();
+
+private:
+
+    using ObserverSet = HeapHashSet<WeakMember<ResizeObserver>>;
+    // Active observers
+    ObserverSet m_observers;
+};
+
+} // namespace blink
+
+#endif