Use DOMHighResTimeStamp for notification time.

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/ExceptionCode.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/dom/IntersectionObserverCallback.h"
 #include "core/dom/IntersectionObserverController.h"
 #include "core/dom/IntersectionObserverEntry.h"
 #include "core/dom/IntersectionObserverInit.h"
 #include "core/dom/NodeIntersectionObserverData.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/layout/LayoutView.h"
+#include "core/timing/DOMWindowPerformance.h"
+#include "core/timing/Performance.h"
 #include "platform/Timer.h"
 #include "wtf/MainThread.h"
 #include <algorithm>
 
 namespace blink {
 
 static void parseRootMargin(String rootMarginParameter, Vector<Length>& rootMargin, ExceptionState& exceptionState)
 {
     // TODO(szager): Make sure this exact syntax and behavior is spec-ed somewhere.
 
@@ skipping 201 matching lines @@
 
 void IntersectionObserver::unobserve(Element* target, ExceptionState&)
 {
     if (!target || !target->intersectionObserverData())
         return;
     // TODO(szager): unobserve callback
     if (IntersectionObservation* observation = target->intersectionObserverData()->getObservationFor(*this))
         observation->disconnect();
 }
 
-void IntersectionObserver::computeIntersectionObservations(double timestamp)
+void IntersectionObserver::computeIntersectionObservations()
 {
     if (!m_root)
         return;
+    Document* callbackDocument = toDocument(m_callback->executionContext());
+    if (!callbackDocument)
+        return;
+    LocalDOMWindow* callbackDOMWindow = callbackDocument->domWindow();
+    if (!callbackDOMWindow)
+        return;
+    DOMHighResTimeStamp timestamp = DOMWindowPerformance::performance(*callbackDOMWindow)->now();
     for (auto& observation : m_observations)
         observation->computeIntersectionObservations(timestamp);
 }
 
 void IntersectionObserver::disconnect()
 {
     for (auto& observation : m_observations)
         observation->clearRootAndRemoveFromTarget();
     m_observations.clear();
 }
@@ skipping 76 matching lines @@
 {
 #if ENABLE(OILPAN)
     visitor->template registerWeakMembers<IntersectionObserver, &IntersectionObserver::clearWeakMembers>(this);
 #endif
     visitor->trace(m_callback);
     visitor->trace(m_observations);
     visitor->trace(m_entries);
 }
 
 } // namespace blink