ResizeObserver pt5: size change notification

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()
+    : m_observersChanged(false)
 {
 }
 
 void ResizeObserverController::addObserver(ResizeObserver& observer)
 {
     m_observers.add(&observer);
 }
 
+size_t ResizeObserverController::gatherObservations(size_t deeperThan)
+{
+    size_t shallowest = ResizeObserverController::kDepthBottom;
+    if (!m_observersChanged)
+        return shallowest;
+    for (auto& observer : m_observers) {
+        size_t depth = observer->gatherObservations(deeperThan);
+        if (depth < shallowest)
+            shallowest = depth;
+    }
+    return shallowest;
+}
+
+bool ResizeObserverController::skippedObservations()
+{
+    for (auto& observer : m_observers) {
+        if (observer->skippedObservations())
+            return true;
+    }
+    return false;
+}
+
+void ResizeObserverController::deliverObservations()
+{
+    m_observersChanged = false;
+    // 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();
+            m_observersChanged = m_observersChanged || observer->hasElementSizeChanged();
+        }
+    }
+}
+
+void ResizeObserverController::clearObservations()
+{
+    for (auto& observer : m_observers)
+        observer->clearObservations();
+}
 
 DEFINE_TRACE(ResizeObserverController)
 {
     visitor->trace(m_observers);
 }
 
 } // namespace blink