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 = observer->gatherObservations() || hasObservations;
+    return hasObservations;
+}
+
+void ResizeObserverController::deliverObservations()
+{
+    // Copy is needed because m_observers might get modified during deliverObservations.
+    HeapVector<Member<ResizeObserver>> observers;
+    copyToVector(m_observers, observers);
+
+    for (auto& observer : observers) {
+        if (observer)
+            observer->deliverObservations();
+    }
+}
+
+void ResizeObserverController::clearObservations()
+{
+    for (auto& observer : m_observers)
+        observer->clearObservations();
+}
+
+DEFINE_TRACE(ResizeObserverController)
+{
+    visitor->trace(m_observers);
+}
+
+} // namespace blink