Initial ResizeObserver implementation

third_party/WebKit/Source/core/observer/ResizeObserverController.cpp

+// 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.
+
+#include "core/observer/ResizeObserverController.h"
+
+#include "core/observer/ResizeObserver.h"
+
+
+namespace blink {
+
+ResizeObserverController::ResizeObserverController()
+{
+}
+
+void ResizeObserverController::addObserver(ResizeObserver& observer)
+{
+    m_observers.add(&observer);
+}
+
+bool ResizeObserverController::gatherObservations()
+{
+    bool hasObservations = false;
+    for (auto& observer : m_observers)
+        hasObservations = hasObservations || observer->gatherObservations();
+    return hasObservations;
+}
+
+void ResizeObserverController::deliverObservations()
+{
+    for (auto& observer : m_observers)
+        observer->deliverObservations();
+}
+
+DEFINE_TRACE(ResizeObserverController)
+{
+    visitor->trace(m_observers);
+}
+
+} // namespace blink