60 
  61 Performance::~Performance()
  62 {
  63 }
  64 
  65 void Performance::contextDestroyed()
  66 {
  67     m_performanceTimelineTaskQueue.close();
  68 
  69     ContextDestructionObserver::contextDestroyed();
  70 }
  71 
  72 double Performance::now() const
  73 {
  74     Seconds now = MonotonicTime::now() - m_timeOrigin;
  75     return reduceTimeResolution(now).milliseconds();
  76 }
  77 
  78 Seconds Performance::reduceTimeResolution(Seconds seconds)
  79 {
  80     double resolution = (100_us).seconds();
  81     double reduced = std::floor(seconds.seconds() / resolution) * resolution;
  82     return Seconds(reduced);
  83 }
  84 
  85 PerformanceNavigation* Performance::navigation()
  86 {
  87     if (!is<Document>(scriptExecutionContext()))
  88         return nullptr;
  89 
  90     ASSERT(isMainThread());
  91     if (!m_navigation)
  92         m_navigation = PerformanceNavigation::create(downcast<Document>(*scriptExecutionContext()).frame());
  93     return m_navigation.get();
  94 }
  95 
  96 PerformanceTiming* Performance::timing()
  97 {
  98     if (!is<Document>(scriptExecutionContext()))
  99         return nullptr;
 100 

  60 
  61 Performance::~Performance()
  62 {
  63 }
  64 
  65 void Performance::contextDestroyed()
  66 {
  67     m_performanceTimelineTaskQueue.close();
  68 
  69     ContextDestructionObserver::contextDestroyed();
  70 }
  71 
  72 double Performance::now() const
  73 {
  74     Seconds now = MonotonicTime::now() - m_timeOrigin;
  75     return reduceTimeResolution(now).milliseconds();
  76 }
  77 
  78 Seconds Performance::reduceTimeResolution(Seconds seconds)
  79 {
  80     double resolution = (1000_us).seconds();
  81     double reduced = std::floor(seconds.seconds() / resolution) * resolution;
  82     return Seconds(reduced);
  83 }
  84 
  85 PerformanceNavigation* Performance::navigation()
  86 {
  87     if (!is<Document>(scriptExecutionContext()))
  88         return nullptr;
  89 
  90     ASSERT(isMainThread());
  91     if (!m_navigation)
  92         m_navigation = PerformanceNavigation::create(downcast<Document>(*scriptExecutionContext()).frame());
  93     return m_navigation.get();
  94 }
  95 
  96 PerformanceTiming* Performance::timing()
  97 {
  98     if (!is<Document>(scriptExecutionContext()))
  99         return nullptr;
 100