Use high precision timestamp for Event.timestamp

third_party/WebKit/Source/core/timing/PerformanceBase.cpp

Index: third_party/WebKit/Source/core/timing/PerformanceBase.cpp
diff --git a/third_party/WebKit/Source/core/timing/PerformanceBase.cpp b/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
index ac075b2a4934013fe6f5e10af681b23e3ec6b359..5e3d6b7ea6abed219a40588f7b51f48706712137 100644
--- a/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
+++ b/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
@@ -415,11 +415,16 @@ void PerformanceBase::deliverObservationsTimerFired(Timer<PerformanceBase>*)
     }
 }
 
+double toSafePrecisionTime(double timeInSeconds)
+{
+    static const double precision = 0.000005; // in seconds
+    return floor(timeInSeconds / precision) * precision;
+}
+
 double PerformanceBase::now() const
 {
     double nowSeconds = monotonicallyIncreasingTime() - m_timeOrigin;
-    const double resolutionSeconds = 0.000005;
-    return 1000.0 * floor(nowSeconds / resolutionSeconds) * resolutionSeconds;
+    return 1000.0 * toSafePrecisionTime(nowSeconds);
 }
 
 DEFINE_TRACE(PerformanceBase)