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);
+}
+
+void ResizeObserverController::gatherObservations()
+{
+    for (auto it = m_observers.begin(); it != m_observers.end(); ++it)

[szager1, 2016/05/23 19:49:12]

for (auto& observer : m_observers)
  observer->gatherObservations();

[atotic1, 2016/05/25 00:15:53]

Done.

+        (**it).gatherObservations();
+}
+
+bool ResizeObserverController::hasObservations()
+{
+    for (auto it = m_observers.begin(); it != m_observers.end(); ++it) {

[szager1, 2016/05/23 19:49:12]

This shouldn't do an iteration.  Consider making
ResizeObserver::gatherObservations() return a bool indicating whether any new
notifications were generated, and then:

void ResizeObserverController::gatherObservations
{
  for (auto& observer : m_observers)
    m_hasNotifications |= observer->gatherObservations();
}

void ResizeObserverController::deliverObservations()
{
  for (auto& observer : m_observers)
    observer->deliverObservations();
  m_hasNotifications = false;
}

[atotic1, 2016/05/25 00:15:53]

That was my original design, broke it apart to experiment with different
algorithms.

Done.

+        if ((**it).hasObservations())
+            return true;
+    }
+    return false;
+}
+
+void ResizeObserverController::deliverObservations()
+{
+    for (auto it = m_observers.begin(); it != m_observers.end(); ++it)

[szager1, 2016/05/23 19:49:12]

ditto iterator syntax.

[atotic1, 2016/05/25 00:15:53]

Done.

+        (**it).deliverObservations();
+}
+
+DEFINE_TRACE(ResizeObserverController)
+{
+    visitor->trace(m_observers);
+}
+
+} // namespace blink