Use intersection observer to control frame throttling

third_party/WebKit/Source/core/dom/IntersectionObserver.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/dom/IntersectionObserver.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/css/parser/CSSParserTokenRange.h"
 #include "core/css/parser/CSSTokenizer.h"
 #include "core/dom/Element.h"
@@ skipping 166 matching lines @@
 }
 
 IntersectionObserver::IntersectionObserver(IntersectionObserverCallback& callback, Node& root, const Vector<Length>& rootMargin, const Vector<float>& thresholds)
     : m_callback(&callback)
     , m_root(&root)
     , m_thresholds(thresholds)
     , m_topMargin(Fixed)
     , m_rightMargin(Fixed)
     , m_bottomMargin(Fixed)
     , m_leftMargin(Fixed)
+    , m_lowLatency(false)
 {
     switch (rootMargin.size()) {
     case 0:
         break;
     case 1:
         m_topMargin = m_rightMargin = m_bottomMargin = m_leftMargin = rootMargin[0];
         break;
     case 2:
         m_topMargin = m_bottomMargin = rootMargin[0];
         m_rightMargin = m_leftMargin = rootMargin[1];
@@ skipping 210 matching lines @@
 
 DEFINE_TRACE(IntersectionObserver)
 {
     visitor->template registerWeakMembers<IntersectionObserver, &IntersectionObserver::clearWeakMembers>(this);
     visitor->trace(m_callback);
     visitor->trace(m_observations);
     visitor->trace(m_entries);
 }
 
 } // namespace blink